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1 | 1 | ================= |
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2 | 2 | IPython reference |
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3 | 3 | ================= |
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4 | 4 | |
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5 | 5 | .. _command_line_options: |
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6 | 6 | |
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7 | 7 | Command-line usage |
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8 | 8 | ================== |
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9 | 9 | |
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10 | 10 | You start IPython with the command:: |
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11 | 11 | |
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12 | 12 | $ ipython [options] files |
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13 | 13 | |
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14 | 14 | .. note:: |
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15 | 15 | |
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16 | 16 | For IPython on Python 3, use ``ipython3`` in place of ``ipython``. |
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17 | 17 | |
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18 | 18 | If invoked with no options, it executes all the files listed in sequence |
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19 | 19 | and drops you into the interpreter while still acknowledging any options |
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20 | 20 | you may have set in your ipython_config.py. This behavior is different from |
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21 | 21 | standard Python, which when called as python -i will only execute one |
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22 | 22 | file and ignore your configuration setup. |
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23 | 23 | |
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24 | 24 | Please note that some of the configuration options are not available at |
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25 | 25 | the command line, simply because they are not practical here. Look into |
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26 | 26 | your configuration files for details on those. There are separate configuration |
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27 | 27 | files for each profile, and the files look like "ipython_config.py" or |
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28 | 28 | "ipython_config_<frontendname>.py". Profile directories look like |
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29 | 29 | "profile_profilename" and are typically installed in the IPYTHONDIR directory, |
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30 | 30 | which defaults to :file:`$HOME/.ipython`. For Windows users, :envvar:`HOME` |
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31 | 31 | resolves to :file:`C:\\Documents and Settings\\YourUserName` in most |
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32 | 32 | instances. |
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33 | 33 | |
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34 | 34 | |
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35 | 35 | Eventloop integration |
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36 | 36 | --------------------- |
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37 | 37 | |
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38 | 38 | Previously IPython had command line options for controlling GUI event loop |
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39 | 39 | integration (-gthread, -qthread, -q4thread, -wthread, -pylab). As of IPython |
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40 | 40 | version 0.11, these have been removed. Please see the new ``%gui`` |
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41 | 41 | magic command or :ref:`this section <gui_support>` for details on the new |
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42 | 42 | interface, or specify the gui at the commandline:: |
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43 | 43 | |
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44 | 44 | $ ipython --gui=qt |
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45 | 45 | |
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46 | 46 | |
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47 | 47 | Command-line Options |
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48 | 48 | -------------------- |
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49 | 49 | |
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50 | 50 | To see the options IPython accepts, use ``ipython --help`` (and you probably |
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51 | 51 | should run the output through a pager such as ``ipython --help | less`` for |
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52 | 52 | more convenient reading). This shows all the options that have a single-word |
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53 | 53 | alias to control them, but IPython lets you configure all of its objects from |
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54 | 54 | the command-line by passing the full class name and a corresponding value; type |
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55 | 55 | ``ipython --help-all`` to see this full list. For example:: |
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56 | 56 | |
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57 | 57 | ipython --matplotlib qt |
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58 | 58 | |
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59 | 59 | is equivalent to:: |
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60 | 60 | |
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61 | 61 | ipython --TerminalIPythonApp.matplotlib='qt' |
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62 | 62 | |
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63 | 63 | Note that in the second form, you *must* use the equal sign, as the expression |
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64 | 64 | is evaluated as an actual Python assignment. While in the above example the |
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65 | 65 | short form is more convenient, only the most common options have a short form, |
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66 | 66 | while any configurable variable in IPython can be set at the command-line by |
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67 | 67 | using the long form. This long form is the same syntax used in the |
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68 | 68 | configuration files, if you want to set these options permanently. |
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69 | 69 | |
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70 | 70 | |
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71 | 71 | Interactive use |
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72 | 72 | =============== |
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73 | 73 | |
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74 | 74 | IPython is meant to work as a drop-in replacement for the standard interactive |
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75 | 75 | interpreter. As such, any code which is valid python should execute normally |
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76 | 76 | under IPython (cases where this is not true should be reported as bugs). It |
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77 | 77 | does, however, offer many features which are not available at a standard python |
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78 | 78 | prompt. What follows is a list of these. |
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79 | 79 | |
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80 | 80 | |
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81 | 81 | Caution for Windows users |
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82 | 82 | ------------------------- |
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83 | 83 | |
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84 | 84 | Windows, unfortunately, uses the '\\' character as a path separator. This is a |
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85 | 85 | terrible choice, because '\\' also represents the escape character in most |
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86 | 86 | modern programming languages, including Python. For this reason, using '/' |
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87 | 87 | character is recommended if you have problems with ``\``. However, in Windows |
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88 | 88 | commands '/' flags options, so you can not use it for the root directory. This |
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89 | 89 | means that paths beginning at the root must be typed in a contrived manner |
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90 | 90 | like: ``%copy \opt/foo/bar.txt \tmp`` |
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91 | 91 | |
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92 | 92 | .. _magic: |
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93 | 93 | |
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94 | 94 | Magic command system |
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95 | 95 | -------------------- |
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96 | 96 | |
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97 | 97 | IPython will treat any line whose first character is a % as a special |
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98 | 98 | call to a 'magic' function. These allow you to control the behavior of |
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99 | 99 | IPython itself, plus a lot of system-type features. They are all |
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100 | 100 | prefixed with a % character, but parameters are given without |
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101 | 101 | parentheses or quotes. |
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102 | 102 | |
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103 | 103 | Lines that begin with ``%%`` signal a *cell magic*: they take as arguments not |
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104 | 104 | only the rest of the current line, but all lines below them as well, in the |
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105 | 105 | current execution block. Cell magics can in fact make arbitrary modifications |
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106 | 106 | to the input they receive, which need not even be valid Python code at all. |
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107 | 107 | They receive the whole block as a single string. |
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108 | 108 | |
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109 | 109 | As a line magic example, the ``%cd`` magic works just like the OS command of |
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110 | 110 | the same name:: |
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111 | 111 | |
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112 | 112 | In [8]: %cd |
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113 | 113 | /home/fperez |
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114 | 114 | |
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115 | 115 | The following uses the builtin ``timeit`` in cell mode:: |
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116 | 116 | |
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117 | 117 | In [10]: %%timeit x = range(10000) |
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118 | 118 | ...: min(x) |
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119 | 119 | ...: max(x) |
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120 | 120 | ...: |
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121 | 121 | 1000 loops, best of 3: 438 us per loop |
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122 | 122 | |
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123 | 123 | In this case, ``x = range(10000)`` is called as the line argument, and the |
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124 | 124 | block with ``min(x)`` and ``max(x)`` is called as the cell body. The |
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125 | 125 | ``timeit`` magic receives both. |
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126 | 126 | |
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127 | 127 | If you have 'automagic' enabled (as it by default), you don't need to type in |
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128 | 128 | the single ``%`` explicitly for line magics; IPython will scan its internal |
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129 | 129 | list of magic functions and call one if it exists. With automagic on you can |
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130 | 130 | then just type ``cd mydir`` to go to directory 'mydir':: |
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131 | 131 | |
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132 | 132 | In [9]: cd mydir |
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133 | 133 | /home/fperez/mydir |
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134 | 134 | |
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135 | 135 | Note that cell magics *always* require an explicit ``%%`` prefix, automagic |
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136 | 136 | calling only works for line magics. |
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137 | 137 | |
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138 | 138 | The automagic system has the lowest possible precedence in name searches, so |
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139 | 139 | defining an identifier with the same name as an existing magic function will |
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140 | 140 | shadow it for automagic use. You can still access the shadowed magic function |
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141 | 141 | by explicitly using the ``%`` character at the beginning of the line. |
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142 | 142 | |
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143 | 143 | An example (with automagic on) should clarify all this: |
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144 | 144 | |
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145 | 145 | .. sourcecode:: ipython |
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146 | 146 | |
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147 | 147 | In [1]: cd ipython # %cd is called by automagic |
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148 | 148 | /home/fperez/ipython |
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149 | 149 | |
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150 | 150 | In [2]: cd=1 # now cd is just a variable |
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151 | 151 | |
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152 | 152 | In [3]: cd .. # and doesn't work as a function anymore |
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153 | 153 | File "<ipython-input-3-9fedb3aff56c>", line 1 |
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154 | 154 | cd .. |
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155 | 155 | ^ |
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156 | 156 | SyntaxError: invalid syntax |
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157 | 157 | |
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158 | 158 | |
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159 | 159 | In [4]: %cd .. # but %cd always works |
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160 | 160 | /home/fperez |
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161 | 161 | |
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162 | 162 | In [5]: del cd # if you remove the cd variable, automagic works again |
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163 | 163 | |
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164 | 164 | In [6]: cd ipython |
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165 | 165 | |
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166 | 166 | /home/fperez/ipython |
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167 | 167 | |
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168 | 168 | Defining your own magics |
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169 | 169 | ++++++++++++++++++++++++ |
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170 | 170 | |
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171 | 171 | There are two main ways to define your own magic functions: from standalone |
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172 | 172 | functions and by inheriting from a base class provided by IPython: |
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173 | 173 | :class:`IPython.core.magic.Magics`. Below we show code you can place in a file |
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174 | 174 | that you load from your configuration, such as any file in the ``startup`` |
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175 | 175 | subdirectory of your default IPython profile. |
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176 | 176 | |
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177 | 177 | First, let us see the simplest case. The following shows how to create a line |
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178 | 178 | magic, a cell one and one that works in both modes, using just plain functions: |
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179 | 179 | |
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180 | 180 | .. sourcecode:: python |
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181 | 181 | |
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182 | 182 | from IPython.core.magic import (register_line_magic, register_cell_magic, |
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183 | 183 | register_line_cell_magic) |
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184 | 184 | |
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185 | 185 | @register_line_magic |
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186 | 186 | def lmagic(line): |
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187 | 187 | "my line magic" |
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188 | 188 |
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189 | 189 | |
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190 | 190 | @register_cell_magic |
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191 | 191 | def cmagic(line, cell): |
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192 | 192 | "my cell magic" |
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193 | 193 | return line, cell |
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194 | 194 | |
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195 | 195 | @register_line_cell_magic |
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196 | 196 | def lcmagic(line, cell=None): |
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197 | 197 | "Magic that works both as %lcmagic and as %%lcmagic" |
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198 | 198 |
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199 |
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199 | print("Called as line magic") | |
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200 | 200 |
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201 | 201 | else: |
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202 |
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202 | print("Called as cell magic") | |
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203 | 203 | return line, cell |
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204 | 204 | |
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205 | 205 | # We delete these to avoid name conflicts for automagic to work |
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206 | 206 | del lmagic, lcmagic |
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207 | 207 | |
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208 | 208 | |
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209 | 209 | You can also create magics of all three kinds by inheriting from the |
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210 | 210 | :class:`IPython.core.magic.Magics` class. This lets you create magics that can |
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211 | 211 | potentially hold state in between calls, and that have full access to the main |
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212 | 212 | IPython object: |
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213 | 213 | |
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214 | 214 | .. sourcecode:: python |
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215 | 215 | |
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216 | 216 | # This code can be put in any Python module, it does not require IPython |
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217 | 217 | # itself to be running already. It only creates the magics subclass but |
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218 | 218 | # doesn't instantiate it yet. |
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219 | from __future__ import print_function | |
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219 | 220 | from IPython.core.magic import (Magics, magics_class, line_magic, |
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220 | 221 | cell_magic, line_cell_magic) |
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221 | 222 | |
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222 | 223 | # The class MUST call this class decorator at creation time |
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223 | 224 | @magics_class |
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224 | 225 | class MyMagics(Magics): |
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225 | 226 | |
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226 | 227 | @line_magic |
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227 | 228 | def lmagic(self, line): |
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228 | 229 | "my line magic" |
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229 |
print |
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230 |
print |
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230 | print("Full access to the main IPython object:", self.shell) | |
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231 | print("Variables in the user namespace:", list(self.shell.user_ns.keys())) | |
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231 | 232 | return line |
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232 | 233 | |
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233 | 234 | @cell_magic |
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234 | 235 | def cmagic(self, line, cell): |
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235 | 236 | "my cell magic" |
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236 | 237 | return line, cell |
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237 | 238 | |
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238 | 239 | @line_cell_magic |
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239 | 240 | def lcmagic(self, line, cell=None): |
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240 | 241 | "Magic that works both as %lcmagic and as %%lcmagic" |
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241 | 242 | if cell is None: |
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242 |
print |
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243 | print("Called as line magic") | |
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243 | 244 | return line |
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244 | 245 | else: |
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245 |
print |
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246 | print("Called as cell magic") | |
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246 | 247 | return line, cell |
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247 | 248 | |
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248 | 249 | |
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249 | 250 | # In order to actually use these magics, you must register them with a |
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250 | 251 | # running IPython. This code must be placed in a file that is loaded once |
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251 | 252 | # IPython is up and running: |
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252 | 253 | ip = get_ipython() |
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253 | 254 | # You can register the class itself without instantiating it. IPython will |
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254 | 255 | # call the default constructor on it. |
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255 | 256 | ip.register_magics(MyMagics) |
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256 | 257 | |
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257 | 258 | If you want to create a class with a different constructor that holds |
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258 | 259 | additional state, then you should always call the parent constructor and |
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259 | 260 | instantiate the class yourself before registration: |
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260 | 261 | |
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261 | 262 | .. sourcecode:: python |
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262 | 263 | |
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263 | 264 | @magics_class |
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264 | 265 | class StatefulMagics(Magics): |
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265 | 266 | "Magics that hold additional state" |
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266 | 267 | |
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267 | 268 | def __init__(self, shell, data): |
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268 | 269 | # You must call the parent constructor |
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269 | 270 | super(StatefulMagics, self).__init__(shell) |
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270 | 271 | self.data = data |
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271 | 272 | |
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272 | 273 | # etc... |
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273 | 274 | |
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274 | 275 | # This class must then be registered with a manually created instance, |
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275 | 276 | # since its constructor has different arguments from the default: |
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276 | 277 | ip = get_ipython() |
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277 | 278 | magics = StatefulMagics(ip, some_data) |
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278 | 279 | ip.register_magics(magics) |
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279 | 280 | |
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280 | 281 | |
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281 | 282 | In earlier versions, IPython had an API for the creation of line magics (cell |
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282 | 283 | magics did not exist at the time) that required you to create functions with a |
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283 | 284 | method-looking signature and to manually pass both the function and the name. |
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284 | 285 | While this API is no longer recommended, it remains indefinitely supported for |
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285 | 286 | backwards compatibility purposes. With the old API, you'd create a magic as |
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286 | 287 | follows: |
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287 | 288 | |
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288 | 289 | .. sourcecode:: python |
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289 | 290 | |
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290 | 291 | def func(self, line): |
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291 |
print |
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292 |
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292 | print("Line magic called with line:", line) | |
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293 | print("IPython object:", self.shell) | |
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293 | 294 | |
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294 | 295 | ip = get_ipython() |
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295 | 296 | # Declare this function as the magic %mycommand |
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296 | 297 | ip.define_magic('mycommand', func) |
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297 | 298 | |
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298 | 299 | Type ``%magic`` for more information, including a list of all available magic |
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299 | 300 | functions at any time and their docstrings. You can also type |
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300 | 301 | ``%magic_function_name?`` (see :ref:`below <dynamic_object_info>` for |
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301 | 302 | information on the '?' system) to get information about any particular magic |
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302 | 303 | function you are interested in. |
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303 | 304 | |
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304 | 305 | The API documentation for the :mod:`IPython.core.magic` module contains the full |
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305 | 306 | docstrings of all currently available magic commands. |
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306 | 307 | |
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307 | 308 | |
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308 | 309 | Access to the standard Python help |
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309 | 310 | ---------------------------------- |
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310 | 311 | |
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311 | 312 | Simply type ``help()`` to access Python's standard help system. You can |
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312 | 313 | also type ``help(object)`` for information about a given object, or |
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313 | 314 | ``help('keyword')`` for information on a keyword. You may need to configure your |
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314 | 315 | PYTHONDOCS environment variable for this feature to work correctly. |
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315 | 316 | |
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316 | 317 | .. _dynamic_object_info: |
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317 | 318 | |
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318 | 319 | Dynamic object information |
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319 | 320 | -------------------------- |
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320 | 321 | |
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321 | 322 | Typing ``?word`` or ``word?`` prints detailed information about an object. If |
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322 | 323 | certain strings in the object are too long (e.g. function signatures) they get |
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323 | 324 | snipped in the center for brevity. This system gives access variable types and |
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324 | 325 | values, docstrings, function prototypes and other useful information. |
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325 | 326 | |
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326 | 327 | If the information will not fit in the terminal, it is displayed in a pager |
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327 | 328 | (``less`` if available, otherwise a basic internal pager). |
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328 | 329 | |
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329 | 330 | Typing ``??word`` or ``word??`` gives access to the full information, including |
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330 | 331 | the source code where possible. Long strings are not snipped. |
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331 | 332 | |
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332 | 333 | The following magic functions are particularly useful for gathering |
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333 | 334 | information about your working environment. You can get more details by |
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334 | 335 | typing ``%magic`` or querying them individually (``%function_name?``); |
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335 | 336 | this is just a summary: |
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336 | 337 | |
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337 | 338 | * **%pdoc <object>**: Print (or run through a pager if too long) the |
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338 | 339 | docstring for an object. If the given object is a class, it will |
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339 | 340 | print both the class and the constructor docstrings. |
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340 | 341 | * **%pdef <object>**: Print the call signature for any callable |
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341 | 342 | object. If the object is a class, print the constructor information. |
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342 | 343 | * **%psource <object>**: Print (or run through a pager if too long) |
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343 | 344 | the source code for an object. |
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344 | 345 | * **%pfile <object>**: Show the entire source file where an object was |
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345 | 346 | defined via a pager, opening it at the line where the object |
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346 | 347 | definition begins. |
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347 | 348 | * **%who/%whos**: These functions give information about identifiers |
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348 | 349 | you have defined interactively (not things you loaded or defined |
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349 | 350 | in your configuration files). %who just prints a list of |
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350 | 351 | identifiers and %whos prints a table with some basic details about |
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351 | 352 | each identifier. |
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352 | 353 | |
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353 | 354 | Note that the dynamic object information functions (?/??, ``%pdoc``, |
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354 | 355 | ``%pfile``, ``%pdef``, ``%psource``) work on object attributes, as well as |
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355 | 356 | directly on variables. For example, after doing ``import os``, you can use |
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356 | 357 | ``os.path.abspath??``. |
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357 | 358 | |
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358 | 359 | .. _readline: |
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359 | 360 | |
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360 | 361 | Readline-based features |
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361 | 362 | ----------------------- |
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362 | 363 | |
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363 | 364 | These features require the GNU readline library, so they won't work if your |
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364 | 365 | Python installation lacks readline support. We will first describe the default |
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365 | 366 | behavior IPython uses, and then how to change it to suit your preferences. |
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366 | 367 | |
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367 | 368 | |
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368 | 369 | Command line completion |
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369 | 370 | +++++++++++++++++++++++ |
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370 | 371 | |
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371 | 372 | At any time, hitting TAB will complete any available python commands or |
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372 | 373 | variable names, and show you a list of the possible completions if |
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373 | 374 | there's no unambiguous one. It will also complete filenames in the |
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374 | 375 | current directory if no python names match what you've typed so far. |
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375 | 376 | |
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376 | 377 | |
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377 | 378 | Search command history |
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378 | 379 | ++++++++++++++++++++++ |
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379 | 380 | |
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380 | 381 | IPython provides two ways for searching through previous input and thus |
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381 | 382 | reduce the need for repetitive typing: |
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382 | 383 | |
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383 | 384 | 1. Start typing, and then use Ctrl-p (previous,up) and Ctrl-n |
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384 | 385 | (next,down) to search through only the history items that match |
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385 | 386 | what you've typed so far. If you use Ctrl-p/Ctrl-n at a blank |
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386 | 387 | prompt, they just behave like normal arrow keys. |
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387 | 388 | 2. Hit Ctrl-r: opens a search prompt. Begin typing and the system |
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388 | 389 | searches your history for lines that contain what you've typed so |
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389 | 390 | far, completing as much as it can. |
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390 | 391 | |
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391 | 392 | |
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392 | 393 | Persistent command history across sessions |
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393 | 394 | ++++++++++++++++++++++++++++++++++++++++++ |
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394 | 395 | |
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395 | 396 | IPython will save your input history when it leaves and reload it next |
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396 | 397 | time you restart it. By default, the history file is named |
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397 | 398 | $IPYTHONDIR/profile_<name>/history.sqlite. This allows you to keep |
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398 | 399 | separate histories related to various tasks: commands related to |
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399 | 400 | numerical work will not be clobbered by a system shell history, for |
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400 | 401 | example. |
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401 | 402 | |
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402 | 403 | |
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403 | 404 | Autoindent |
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404 | 405 | ++++++++++ |
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405 | 406 | |
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406 | 407 | IPython can recognize lines ending in ':' and indent the next line, |
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407 | 408 | while also un-indenting automatically after 'raise' or 'return'. |
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408 | 409 | |
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409 | 410 | This feature uses the readline library, so it will honor your |
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410 | 411 | :file:`~/.inputrc` configuration (or whatever file your INPUTRC variable points |
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411 | 412 | to). Adding the following lines to your :file:`.inputrc` file can make |
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412 | 413 | indenting/unindenting more convenient (M-i indents, M-u unindents):: |
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413 | 414 | |
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414 | 415 | # if you don't already have a ~/.inputrc file, you need this include: |
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415 | 416 | $include /etc/inputrc |
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416 | 417 | |
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417 | 418 | $if Python |
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418 | 419 | "\M-i": " " |
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419 | 420 | "\M-u": "\d\d\d\d" |
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420 | 421 | $endif |
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421 | 422 | |
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422 | 423 | Note that there are 4 spaces between the quote marks after "M-i" above. |
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423 | 424 | |
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424 | 425 | .. warning:: |
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425 | 426 | |
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426 | 427 | Setting the above indents will cause problems with unicode text entry in |
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427 | 428 | the terminal. |
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428 | 429 | |
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429 | 430 | .. warning:: |
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430 | 431 | |
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431 | 432 | Autoindent is ON by default, but it can cause problems with the pasting of |
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432 | 433 | multi-line indented code (the pasted code gets re-indented on each line). A |
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433 | 434 | magic function %autoindent allows you to toggle it on/off at runtime. You |
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434 | 435 | can also disable it permanently on in your :file:`ipython_config.py` file |
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435 | 436 | (set TerminalInteractiveShell.autoindent=False). |
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436 | 437 | |
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437 | 438 | If you want to paste multiple lines in the terminal, it is recommended that |
|
438 | 439 | you use ``%paste``. |
|
439 | 440 | |
|
440 | 441 | |
|
441 | 442 | Customizing readline behavior |
|
442 | 443 | +++++++++++++++++++++++++++++ |
|
443 | 444 | |
|
444 | 445 | All these features are based on the GNU readline library, which has an |
|
445 | 446 | extremely customizable interface. Normally, readline is configured via a |
|
446 | 447 | file which defines the behavior of the library; the details of the |
|
447 | 448 | syntax for this can be found in the readline documentation available |
|
448 | 449 | with your system or on the Internet. IPython doesn't read this file (if |
|
449 | 450 | it exists) directly, but it does support passing to readline valid |
|
450 | 451 | options via a simple interface. In brief, you can customize readline by |
|
451 | 452 | setting the following options in your configuration file (note |
|
452 | 453 | that these options can not be specified at the command line): |
|
453 | 454 | |
|
454 | 455 | * **readline_parse_and_bind**: this holds a list of strings to be executed |
|
455 | 456 | via a readline.parse_and_bind() command. The syntax for valid commands |
|
456 | 457 | of this kind can be found by reading the documentation for the GNU |
|
457 | 458 | readline library, as these commands are of the kind which readline |
|
458 | 459 | accepts in its configuration file. |
|
459 | 460 | * **readline_remove_delims**: a string of characters to be removed |
|
460 | 461 | from the default word-delimiters list used by readline, so that |
|
461 | 462 | completions may be performed on strings which contain them. Do not |
|
462 | 463 | change the default value unless you know what you're doing. |
|
463 | 464 | |
|
464 | 465 | You will find the default values in your configuration file. |
|
465 | 466 | |
|
466 | 467 | |
|
467 | 468 | Session logging and restoring |
|
468 | 469 | ----------------------------- |
|
469 | 470 | |
|
470 | 471 | You can log all input from a session either by starting IPython with the |
|
471 | 472 | command line switch ``--logfile=foo.py`` (see :ref:`here <command_line_options>`) |
|
472 | 473 | or by activating the logging at any moment with the magic function %logstart. |
|
473 | 474 | |
|
474 | 475 | Log files can later be reloaded by running them as scripts and IPython |
|
475 | 476 | will attempt to 'replay' the log by executing all the lines in it, thus |
|
476 | 477 | restoring the state of a previous session. This feature is not quite |
|
477 | 478 | perfect, but can still be useful in many cases. |
|
478 | 479 | |
|
479 | 480 | The log files can also be used as a way to have a permanent record of |
|
480 | 481 | any code you wrote while experimenting. Log files are regular text files |
|
481 | 482 | which you can later open in your favorite text editor to extract code or |
|
482 | 483 | to 'clean them up' before using them to replay a session. |
|
483 | 484 | |
|
484 | 485 | The `%logstart` function for activating logging in mid-session is used as |
|
485 | 486 | follows:: |
|
486 | 487 | |
|
487 | 488 | %logstart [log_name [log_mode]] |
|
488 | 489 | |
|
489 | 490 | If no name is given, it defaults to a file named 'ipython_log.py' in your |
|
490 | 491 | current working directory, in 'rotate' mode (see below). |
|
491 | 492 | |
|
492 | 493 | '%logstart name' saves to file 'name' in 'backup' mode. It saves your |
|
493 | 494 | history up to that point and then continues logging. |
|
494 | 495 | |
|
495 | 496 | %logstart takes a second optional parameter: logging mode. This can be |
|
496 | 497 | one of (note that the modes are given unquoted): |
|
497 | 498 | |
|
498 | 499 | * [over:] overwrite existing log_name. |
|
499 | 500 | * [backup:] rename (if exists) to log_name~ and start log_name. |
|
500 | 501 | * [append:] well, that says it. |
|
501 | 502 | * [rotate:] create rotating logs log_name.1~, log_name.2~, etc. |
|
502 | 503 | |
|
503 | 504 | The %logoff and %logon functions allow you to temporarily stop and |
|
504 | 505 | resume logging to a file which had previously been started with |
|
505 | 506 | %logstart. They will fail (with an explanation) if you try to use them |
|
506 | 507 | before logging has been started. |
|
507 | 508 | |
|
508 | 509 | .. _system_shell_access: |
|
509 | 510 | |
|
510 | 511 | System shell access |
|
511 | 512 | ------------------- |
|
512 | 513 | |
|
513 | 514 | Any input line beginning with a ! character is passed verbatim (minus |
|
514 | 515 | the !, of course) to the underlying operating system. For example, |
|
515 | 516 | typing ``!ls`` will run 'ls' in the current directory. |
|
516 | 517 | |
|
517 | 518 | Manual capture of command output |
|
518 | 519 | -------------------------------- |
|
519 | 520 | |
|
520 | 521 | You can assign the result of a system command to a Python variable with the |
|
521 | 522 | syntax ``myfiles = !ls``. This gets machine readable output from stdout |
|
522 | 523 | (e.g. without colours), and splits on newlines. To explicitly get this sort of |
|
523 | 524 | output without assigning to a variable, use two exclamation marks (``!!ls``) or |
|
524 | 525 | the ``%sx`` magic command. |
|
525 | 526 | |
|
526 | 527 | The captured list has some convenience features. ``myfiles.n`` or ``myfiles.s`` |
|
527 | 528 | returns a string delimited by newlines or spaces, respectively. ``myfiles.p`` |
|
528 | 529 | produces `path objects <http://pypi.python.org/pypi/path.py>`_ from the list items. |
|
529 | 530 | See :ref:`string_lists` for details. |
|
530 | 531 | |
|
531 | 532 | IPython also allows you to expand the value of python variables when |
|
532 | 533 | making system calls. Wrap variables or expressions in {braces}:: |
|
533 | 534 | |
|
534 | 535 | In [1]: pyvar = 'Hello world' |
|
535 | 536 | In [2]: !echo "A python variable: {pyvar}" |
|
536 | 537 | A python variable: Hello world |
|
537 | 538 | In [3]: import math |
|
538 | 539 | In [4]: x = 8 |
|
539 | 540 | In [5]: !echo {math.factorial(x)} |
|
540 | 541 | 40320 |
|
541 | 542 | |
|
542 | 543 | For simple cases, you can alternatively prepend $ to a variable name:: |
|
543 | 544 | |
|
544 | 545 | In [6]: !echo $sys.argv |
|
545 | 546 | [/home/fperez/usr/bin/ipython] |
|
546 | 547 | In [7]: !echo "A system variable: $$HOME" # Use $$ for literal $ |
|
547 | 548 | A system variable: /home/fperez |
|
548 | 549 | |
|
549 | 550 | System command aliases |
|
550 | 551 | ---------------------- |
|
551 | 552 | |
|
552 | 553 | The %alias magic function allows you to define magic functions which are in fact |
|
553 | 554 | system shell commands. These aliases can have parameters. |
|
554 | 555 | |
|
555 | 556 | ``%alias alias_name cmd`` defines 'alias_name' as an alias for 'cmd' |
|
556 | 557 | |
|
557 | 558 | Then, typing ``alias_name params`` will execute the system command 'cmd |
|
558 | 559 | params' (from your underlying operating system). |
|
559 | 560 | |
|
560 | 561 | You can also define aliases with parameters using %s specifiers (one per |
|
561 | 562 | parameter). The following example defines the parts function as an |
|
562 | 563 | alias to the command 'echo first %s second %s' where each %s will be |
|
563 | 564 | replaced by a positional parameter to the call to %parts:: |
|
564 | 565 | |
|
565 | 566 | In [1]: %alias parts echo first %s second %s |
|
566 | 567 | In [2]: parts A B |
|
567 | 568 | first A second B |
|
568 | 569 | In [3]: parts A |
|
569 | 570 | ERROR: Alias <parts> requires 2 arguments, 1 given. |
|
570 | 571 | |
|
571 | 572 | If called with no parameters, %alias prints the table of currently |
|
572 | 573 | defined aliases. |
|
573 | 574 | |
|
574 | 575 | The %rehashx magic allows you to load your entire $PATH as |
|
575 | 576 | ipython aliases. See its docstring for further details. |
|
576 | 577 | |
|
577 | 578 | |
|
578 | 579 | .. _dreload: |
|
579 | 580 | |
|
580 | 581 | Recursive reload |
|
581 | 582 | ---------------- |
|
582 | 583 | |
|
583 | 584 | The :mod:`IPython.lib.deepreload` module allows you to recursively reload a |
|
584 | 585 | module: changes made to any of its dependencies will be reloaded without |
|
585 | 586 | having to exit. To start using it, do:: |
|
586 | 587 | |
|
587 | 588 | from IPython.lib.deepreload import reload as dreload |
|
588 | 589 | |
|
589 | 590 | |
|
590 | 591 | Verbose and colored exception traceback printouts |
|
591 | 592 | ------------------------------------------------- |
|
592 | 593 | |
|
593 | 594 | IPython provides the option to see very detailed exception tracebacks, |
|
594 | 595 | which can be especially useful when debugging large programs. You can |
|
595 | 596 | run any Python file with the %run function to benefit from these |
|
596 | 597 | detailed tracebacks. Furthermore, both normal and verbose tracebacks can |
|
597 | 598 | be colored (if your terminal supports it) which makes them much easier |
|
598 | 599 | to parse visually. |
|
599 | 600 | |
|
600 | 601 | See the magic xmode and colors functions for details (just type %magic). |
|
601 | 602 | |
|
602 | 603 | These features are basically a terminal version of Ka-Ping Yee's cgitb |
|
603 | 604 | module, now part of the standard Python library. |
|
604 | 605 | |
|
605 | 606 | |
|
606 | 607 | .. _input_caching: |
|
607 | 608 | |
|
608 | 609 | Input caching system |
|
609 | 610 | -------------------- |
|
610 | 611 | |
|
611 | 612 | IPython offers numbered prompts (In/Out) with input and output caching |
|
612 | 613 | (also referred to as 'input history'). All input is saved and can be |
|
613 | 614 | retrieved as variables (besides the usual arrow key recall), in |
|
614 | 615 | addition to the %rep magic command that brings a history entry |
|
615 | 616 | up for editing on the next command line. |
|
616 | 617 | |
|
617 | 618 | The following GLOBAL variables always exist (so don't overwrite them!): |
|
618 | 619 | |
|
619 | 620 | * _i, _ii, _iii: store previous, next previous and next-next previous inputs. |
|
620 | 621 | * In, _ih : a list of all inputs; _ih[n] is the input from line n. If you |
|
621 | 622 | overwrite In with a variable of your own, you can remake the assignment to the |
|
622 | 623 | internal list with a simple ``In=_ih``. |
|
623 | 624 | |
|
624 | 625 | Additionally, global variables named _i<n> are dynamically created (<n> |
|
625 | 626 | being the prompt counter), so ``_i<n> == _ih[<n>] == In[<n>]``. |
|
626 | 627 | |
|
627 | 628 | For example, what you typed at prompt 14 is available as _i14, _ih[14] |
|
628 | 629 | and In[14]. |
|
629 | 630 | |
|
630 | 631 | This allows you to easily cut and paste multi line interactive prompts |
|
631 | 632 | by printing them out: they print like a clean string, without prompt |
|
632 | 633 | characters. You can also manipulate them like regular variables (they |
|
633 | 634 | are strings), modify or exec them (typing ``exec _i9`` will re-execute the |
|
634 | 635 | contents of input prompt 9. |
|
635 | 636 | |
|
636 | 637 | You can also re-execute multiple lines of input easily by using the |
|
637 | 638 | magic %rerun or %macro functions. The macro system also allows you to re-execute |
|
638 | 639 | previous lines which include magic function calls (which require special |
|
639 | 640 | processing). Type %macro? for more details on the macro system. |
|
640 | 641 | |
|
641 | 642 | A history function %hist allows you to see any part of your input |
|
642 | 643 | history by printing a range of the _i variables. |
|
643 | 644 | |
|
644 | 645 | You can also search ('grep') through your history by typing |
|
645 | 646 | ``%hist -g somestring``. This is handy for searching for URLs, IP addresses, |
|
646 | 647 | etc. You can bring history entries listed by '%hist -g' up for editing |
|
647 | 648 | with the %recall command, or run them immediately with %rerun. |
|
648 | 649 | |
|
649 | 650 | .. _output_caching: |
|
650 | 651 | |
|
651 | 652 | Output caching system |
|
652 | 653 | --------------------- |
|
653 | 654 | |
|
654 | 655 | For output that is returned from actions, a system similar to the input |
|
655 | 656 | cache exists but using _ instead of _i. Only actions that produce a |
|
656 | 657 | result (NOT assignments, for example) are cached. If you are familiar |
|
657 | 658 | with Mathematica, IPython's _ variables behave exactly like |
|
658 | 659 | Mathematica's % variables. |
|
659 | 660 | |
|
660 | 661 | The following GLOBAL variables always exist (so don't overwrite them!): |
|
661 | 662 | |
|
662 | 663 | * [_] (a single underscore) : stores previous output, like Python's |
|
663 | 664 | default interpreter. |
|
664 | 665 | * [__] (two underscores): next previous. |
|
665 | 666 | * [___] (three underscores): next-next previous. |
|
666 | 667 | |
|
667 | 668 | Additionally, global variables named _<n> are dynamically created (<n> |
|
668 | 669 | being the prompt counter), such that the result of output <n> is always |
|
669 | 670 | available as _<n> (don't use the angle brackets, just the number, e.g. |
|
670 | 671 | _21). |
|
671 | 672 | |
|
672 | 673 | These variables are also stored in a global dictionary (not a |
|
673 | 674 | list, since it only has entries for lines which returned a result) |
|
674 | 675 | available under the names _oh and Out (similar to _ih and In). So the |
|
675 | 676 | output from line 12 can be obtained as _12, Out[12] or _oh[12]. If you |
|
676 | 677 | accidentally overwrite the Out variable you can recover it by typing |
|
677 | 678 | 'Out=_oh' at the prompt. |
|
678 | 679 | |
|
679 | 680 | This system obviously can potentially put heavy memory demands on your |
|
680 | 681 | system, since it prevents Python's garbage collector from removing any |
|
681 | 682 | previously computed results. You can control how many results are kept |
|
682 | 683 | in memory with the option (at the command line or in your configuration |
|
683 | 684 | file) cache_size. If you set it to 0, the whole system is completely |
|
684 | 685 | disabled and the prompts revert to the classic '>>>' of normal Python. |
|
685 | 686 | |
|
686 | 687 | |
|
687 | 688 | Directory history |
|
688 | 689 | ----------------- |
|
689 | 690 | |
|
690 | 691 | Your history of visited directories is kept in the global list _dh, and |
|
691 | 692 | the magic %cd command can be used to go to any entry in that list. The |
|
692 | 693 | %dhist command allows you to view this history. Do ``cd -<TAB>`` to |
|
693 | 694 | conveniently view the directory history. |
|
694 | 695 | |
|
695 | 696 | |
|
696 | 697 | Automatic parentheses and quotes |
|
697 | 698 | -------------------------------- |
|
698 | 699 | |
|
699 | 700 | These features were adapted from Nathan Gray's LazyPython. They are |
|
700 | 701 | meant to allow less typing for common situations. |
|
701 | 702 | |
|
702 | 703 | |
|
703 | 704 | Automatic parentheses |
|
704 | 705 | +++++++++++++++++++++ |
|
705 | 706 | |
|
706 | 707 | Callable objects (i.e. functions, methods, etc) can be invoked like this |
|
707 | 708 | (notice the commas between the arguments):: |
|
708 | 709 | |
|
709 | 710 | In [1]: callable_ob arg1, arg2, arg3 |
|
710 | 711 | ------> callable_ob(arg1, arg2, arg3) |
|
711 | 712 | |
|
712 | 713 | You can force automatic parentheses by using '/' as the first character |
|
713 | 714 | of a line. For example:: |
|
714 | 715 | |
|
715 | 716 | In [2]: /globals # becomes 'globals()' |
|
716 | 717 | |
|
717 | 718 | Note that the '/' MUST be the first character on the line! This won't work:: |
|
718 | 719 | |
|
719 | 720 | In [3]: print /globals # syntax error |
|
720 | 721 | |
|
721 | 722 | In most cases the automatic algorithm should work, so you should rarely |
|
722 | 723 | need to explicitly invoke /. One notable exception is if you are trying |
|
723 | 724 | to call a function with a list of tuples as arguments (the parenthesis |
|
724 | 725 | will confuse IPython):: |
|
725 | 726 | |
|
726 | 727 | In [4]: zip (1,2,3),(4,5,6) # won't work |
|
727 | 728 | |
|
728 | 729 | but this will work:: |
|
729 | 730 | |
|
730 | 731 | In [5]: /zip (1,2,3),(4,5,6) |
|
731 | 732 | ------> zip ((1,2,3),(4,5,6)) |
|
732 | 733 | Out[5]: [(1, 4), (2, 5), (3, 6)] |
|
733 | 734 | |
|
734 | 735 | IPython tells you that it has altered your command line by displaying |
|
735 | 736 | the new command line preceded by ->. e.g.:: |
|
736 | 737 | |
|
737 | 738 | In [6]: callable list |
|
738 | 739 | ------> callable(list) |
|
739 | 740 | |
|
740 | 741 | |
|
741 | 742 | Automatic quoting |
|
742 | 743 | +++++++++++++++++ |
|
743 | 744 | |
|
744 | 745 | You can force automatic quoting of a function's arguments by using ',' |
|
745 | 746 | or ';' as the first character of a line. For example:: |
|
746 | 747 | |
|
747 | 748 | In [1]: ,my_function /home/me # becomes my_function("/home/me") |
|
748 | 749 | |
|
749 | 750 | If you use ';' the whole argument is quoted as a single string, while ',' splits |
|
750 | 751 | on whitespace:: |
|
751 | 752 | |
|
752 | 753 | In [2]: ,my_function a b c # becomes my_function("a","b","c") |
|
753 | 754 | |
|
754 | 755 | In [3]: ;my_function a b c # becomes my_function("a b c") |
|
755 | 756 | |
|
756 | 757 | Note that the ',' or ';' MUST be the first character on the line! This |
|
757 | 758 | won't work:: |
|
758 | 759 | |
|
759 | 760 | In [4]: x = ,my_function /home/me # syntax error |
|
760 | 761 | |
|
761 | 762 | IPython as your default Python environment |
|
762 | 763 | ========================================== |
|
763 | 764 | |
|
764 | 765 | Python honors the environment variable :envvar:`PYTHONSTARTUP` and will |
|
765 | 766 | execute at startup the file referenced by this variable. If you put the |
|
766 | 767 | following code at the end of that file, then IPython will be your working |
|
767 | 768 | environment anytime you start Python:: |
|
768 | 769 | |
|
769 | 770 | import os, IPython |
|
770 | 771 | os.environ['PYTHONSTARTUP'] = '' # Prevent running this again |
|
771 | 772 | IPython.start_ipython() |
|
772 | 773 | raise SystemExit |
|
773 | 774 | |
|
774 | 775 | The ``raise SystemExit`` is needed to exit Python when |
|
775 | 776 | it finishes, otherwise you'll be back at the normal Python '>>>' |
|
776 | 777 | prompt. |
|
777 | 778 | |
|
778 | 779 | This is probably useful to developers who manage multiple Python |
|
779 | 780 | versions and don't want to have correspondingly multiple IPython |
|
780 | 781 | versions. Note that in this mode, there is no way to pass IPython any |
|
781 | 782 | command-line options, as those are trapped first by Python itself. |
|
782 | 783 | |
|
783 | 784 | .. _Embedding: |
|
784 | 785 | |
|
785 | 786 | Embedding IPython |
|
786 | 787 | ================= |
|
787 | 788 | |
|
788 | 789 | You can start a regular IPython session with |
|
789 | 790 | |
|
790 | 791 | .. sourcecode:: python |
|
791 | 792 | |
|
792 | 793 | import IPython |
|
793 | 794 | IPython.start_ipython() |
|
794 | 795 | |
|
795 | 796 | at any point in your program. This will load IPython configuration, |
|
796 | 797 | startup files, and everything, just as if it were a normal IPython session. |
|
797 | 798 | In addition to this, |
|
798 | 799 | it is possible to embed an IPython instance inside your own Python programs. |
|
799 | 800 | This allows you to evaluate dynamically the state of your code, |
|
800 | 801 | operate with your variables, analyze them, etc. Note however that |
|
801 | 802 | any changes you make to values while in the shell do not propagate back |
|
802 | 803 | to the running code, so it is safe to modify your values because you |
|
803 | 804 | won't break your code in bizarre ways by doing so. |
|
804 | 805 | |
|
805 | 806 | .. note:: |
|
806 | 807 | |
|
807 | 808 | At present, embedding IPython cannot be done from inside IPython. |
|
808 | 809 | Run the code samples below outside IPython. |
|
809 | 810 | |
|
810 | 811 | This feature allows you to easily have a fully functional python |
|
811 | 812 | environment for doing object introspection anywhere in your code with a |
|
812 | 813 | simple function call. In some cases a simple print statement is enough, |
|
813 | 814 | but if you need to do more detailed analysis of a code fragment this |
|
814 | 815 | feature can be very valuable. |
|
815 | 816 | |
|
816 | 817 | It can also be useful in scientific computing situations where it is |
|
817 | 818 | common to need to do some automatic, computationally intensive part and |
|
818 | 819 | then stop to look at data, plots, etc. |
|
819 | 820 | Opening an IPython instance will give you full access to your data and |
|
820 | 821 | functions, and you can resume program execution once you are done with |
|
821 | 822 | the interactive part (perhaps to stop again later, as many times as |
|
822 | 823 | needed). |
|
823 | 824 | |
|
824 | 825 | The following code snippet is the bare minimum you need to include in |
|
825 | 826 | your Python programs for this to work (detailed examples follow later):: |
|
826 | 827 | |
|
827 | 828 | from IPython import embed |
|
828 | 829 | |
|
829 | 830 | embed() # this call anywhere in your program will start IPython |
|
830 | 831 | |
|
831 | 832 | .. note:: |
|
832 | 833 | |
|
833 | 834 | As of 0.13, you can embed an IPython *kernel*, for use with qtconsole, |
|
834 | 835 | etc. via ``IPython.embed_kernel()`` instead of ``IPython.embed()``. |
|
835 | 836 | It should function just the same as regular embed, but you connect |
|
836 | 837 | an external frontend rather than IPython starting up in the local |
|
837 | 838 | terminal. |
|
838 | 839 | |
|
839 | 840 | You can run embedded instances even in code which is itself being run at |
|
840 | 841 | the IPython interactive prompt with '%run <filename>'. Since it's easy |
|
841 | 842 | to get lost as to where you are (in your top-level IPython or in your |
|
842 | 843 | embedded one), it's a good idea in such cases to set the in/out prompts |
|
843 | 844 | to something different for the embedded instances. The code examples |
|
844 | 845 | below illustrate this. |
|
845 | 846 | |
|
846 | 847 | You can also have multiple IPython instances in your program and open |
|
847 | 848 | them separately, for example with different options for data |
|
848 | 849 | presentation. If you close and open the same instance multiple times, |
|
849 | 850 | its prompt counters simply continue from each execution to the next. |
|
850 | 851 | |
|
851 | 852 | Please look at the docstrings in the :mod:`~IPython.frontend.terminal.embed` |
|
852 | 853 | module for more details on the use of this system. |
|
853 | 854 | |
|
854 | 855 | The following sample file illustrating how to use the embedding |
|
855 | 856 | functionality is provided in the examples directory as example-embed.py. |
|
856 | 857 | It should be fairly self-explanatory: |
|
857 | 858 | |
|
858 | 859 | .. literalinclude:: ../../../examples/core/example-embed.py |
|
859 | 860 | :language: python |
|
860 | 861 | |
|
861 | 862 | Once you understand how the system functions, you can use the following |
|
862 | 863 | code fragments in your programs which are ready for cut and paste: |
|
863 | 864 | |
|
864 | 865 | .. literalinclude:: ../../../examples/core/example-embed-short.py |
|
865 | 866 | :language: python |
|
866 | 867 | |
|
867 | 868 | Using the Python debugger (pdb) |
|
868 | 869 | =============================== |
|
869 | 870 | |
|
870 | 871 | Running entire programs via pdb |
|
871 | 872 | ------------------------------- |
|
872 | 873 | |
|
873 | 874 | pdb, the Python debugger, is a powerful interactive debugger which |
|
874 | 875 | allows you to step through code, set breakpoints, watch variables, |
|
875 | 876 | etc. IPython makes it very easy to start any script under the control |
|
876 | 877 | of pdb, regardless of whether you have wrapped it into a 'main()' |
|
877 | 878 | function or not. For this, simply type '%run -d myscript' at an |
|
878 | 879 | IPython prompt. See the %run command's documentation (via '%run?' or |
|
879 | 880 | in Sec. magic_ for more details, including how to control where pdb |
|
880 | 881 | will stop execution first. |
|
881 | 882 | |
|
882 | 883 | For more information on the use of the pdb debugger, read the included |
|
883 | 884 | pdb.doc file (part of the standard Python distribution). On a stock |
|
884 | 885 | Linux system it is located at /usr/lib/python2.3/pdb.doc, but the |
|
885 | 886 | easiest way to read it is by using the help() function of the pdb module |
|
886 | 887 | as follows (in an IPython prompt):: |
|
887 | 888 | |
|
888 | 889 | In [1]: import pdb |
|
889 | 890 | In [2]: pdb.help() |
|
890 | 891 | |
|
891 | 892 | This will load the pdb.doc document in a file viewer for you automatically. |
|
892 | 893 | |
|
893 | 894 | |
|
894 | 895 | Automatic invocation of pdb on exceptions |
|
895 | 896 | ----------------------------------------- |
|
896 | 897 | |
|
897 | 898 | IPython, if started with the ``--pdb`` option (or if the option is set in |
|
898 | 899 | your config file) can call the Python pdb debugger every time your code |
|
899 | 900 | triggers an uncaught exception. This feature |
|
900 | 901 | can also be toggled at any time with the %pdb magic command. This can be |
|
901 | 902 | extremely useful in order to find the origin of subtle bugs, because pdb |
|
902 | 903 | opens up at the point in your code which triggered the exception, and |
|
903 | 904 | while your program is at this point 'dead', all the data is still |
|
904 | 905 | available and you can walk up and down the stack frame and understand |
|
905 | 906 | the origin of the problem. |
|
906 | 907 | |
|
907 | 908 | Furthermore, you can use these debugging facilities both with the |
|
908 | 909 | embedded IPython mode and without IPython at all. For an embedded shell |
|
909 | 910 | (see sec. Embedding_), simply call the constructor with |
|
910 | 911 | ``--pdb`` in the argument string and pdb will automatically be called if an |
|
911 | 912 | uncaught exception is triggered by your code. |
|
912 | 913 | |
|
913 | 914 | For stand-alone use of the feature in your programs which do not use |
|
914 | 915 | IPython at all, put the following lines toward the top of your 'main' |
|
915 | 916 | routine:: |
|
916 | 917 | |
|
917 | 918 | import sys |
|
918 | 919 | from IPython.core import ultratb |
|
919 | 920 | sys.excepthook = ultratb.FormattedTB(mode='Verbose', |
|
920 | 921 | color_scheme='Linux', call_pdb=1) |
|
921 | 922 | |
|
922 | 923 | The mode keyword can be either 'Verbose' or 'Plain', giving either very |
|
923 | 924 | detailed or normal tracebacks respectively. The color_scheme keyword can |
|
924 | 925 | be one of 'NoColor', 'Linux' (default) or 'LightBG'. These are the same |
|
925 | 926 | options which can be set in IPython with ``--colors`` and ``--xmode``. |
|
926 | 927 | |
|
927 | 928 | This will give any of your programs detailed, colored tracebacks with |
|
928 | 929 | automatic invocation of pdb. |
|
929 | 930 | |
|
930 | 931 | |
|
931 | 932 | Extensions for syntax processing |
|
932 | 933 | ================================ |
|
933 | 934 | |
|
934 | 935 | This isn't for the faint of heart, because the potential for breaking |
|
935 | 936 | things is quite high. But it can be a very powerful and useful feature. |
|
936 | 937 | In a nutshell, you can redefine the way IPython processes the user input |
|
937 | 938 | line to accept new, special extensions to the syntax without needing to |
|
938 | 939 | change any of IPython's own code. |
|
939 | 940 | |
|
940 | 941 | In the IPython/extensions directory you will find some examples |
|
941 | 942 | supplied, which we will briefly describe now. These can be used 'as is' |
|
942 | 943 | (and both provide very useful functionality), or you can use them as a |
|
943 | 944 | starting point for writing your own extensions. |
|
944 | 945 | |
|
945 | 946 | .. _pasting_with_prompts: |
|
946 | 947 | |
|
947 | 948 | Pasting of code starting with Python or IPython prompts |
|
948 | 949 | ------------------------------------------------------- |
|
949 | 950 | |
|
950 | 951 | IPython is smart enough to filter out input prompts, be they plain Python ones |
|
951 | 952 | (``>>>`` and ``...``) or IPython ones (``In [N]:`` and ``...:``). You can |
|
952 | 953 | therefore copy and paste from existing interactive sessions without worry. |
|
953 | 954 | |
|
954 | 955 | The following is a 'screenshot' of how things work, copying an example from the |
|
955 | 956 | standard Python tutorial:: |
|
956 | 957 | |
|
957 | 958 | In [1]: >>> # Fibonacci series: |
|
958 | 959 | |
|
959 | 960 | In [2]: ... # the sum of two elements defines the next |
|
960 | 961 | |
|
961 | 962 | In [3]: ... a, b = 0, 1 |
|
962 | 963 | |
|
963 | 964 | In [4]: >>> while b < 10: |
|
964 |
...: ... print |
|
|
965 | ...: ... print(b) | |
|
965 | 966 | ...: ... a, b = b, a+b |
|
966 | 967 | ...: |
|
967 | 968 | 1 |
|
968 | 969 | 1 |
|
969 | 970 | 2 |
|
970 | 971 | 3 |
|
971 | 972 | 5 |
|
972 | 973 | 8 |
|
973 | 974 | |
|
974 | 975 | And pasting from IPython sessions works equally well:: |
|
975 | 976 | |
|
976 | 977 | In [1]: In [5]: def f(x): |
|
977 | 978 | ...: ...: "A simple function" |
|
978 | 979 | ...: ...: return x**2 |
|
979 | 980 | ...: ...: |
|
980 | 981 | |
|
981 | 982 | In [2]: f(3) |
|
982 | 983 | Out[2]: 9 |
|
983 | 984 | |
|
984 | 985 | .. _gui_support: |
|
985 | 986 | |
|
986 | 987 | GUI event loop support |
|
987 | 988 | ====================== |
|
988 | 989 | |
|
989 | 990 | .. versionadded:: 0.11 |
|
990 | 991 | The ``%gui`` magic and :mod:`IPython.lib.inputhook`. |
|
991 | 992 | |
|
992 | 993 | IPython has excellent support for working interactively with Graphical User |
|
993 | 994 | Interface (GUI) toolkits, such as wxPython, PyQt4/PySide, PyGTK and Tk. This is |
|
994 | 995 | implemented using Python's builtin ``PyOSInputHook`` hook. This implementation |
|
995 | 996 | is extremely robust compared to our previous thread-based version. The |
|
996 | 997 | advantages of this are: |
|
997 | 998 | |
|
998 | 999 | * GUIs can be enabled and disabled dynamically at runtime. |
|
999 | 1000 | * The active GUI can be switched dynamically at runtime. |
|
1000 | 1001 | * In some cases, multiple GUIs can run simultaneously with no problems. |
|
1001 | 1002 | * There is a developer API in :mod:`IPython.lib.inputhook` for customizing |
|
1002 | 1003 | all of these things. |
|
1003 | 1004 | |
|
1004 | 1005 | For users, enabling GUI event loop integration is simple. You simple use the |
|
1005 | 1006 | ``%gui`` magic as follows:: |
|
1006 | 1007 | |
|
1007 | 1008 | %gui [GUINAME] |
|
1008 | 1009 | |
|
1009 | 1010 | With no arguments, ``%gui`` removes all GUI support. Valid ``GUINAME`` |
|
1010 | 1011 | arguments are ``wx``, ``qt``, ``gtk`` and ``tk``. |
|
1011 | 1012 | |
|
1012 | 1013 | Thus, to use wxPython interactively and create a running :class:`wx.App` |
|
1013 | 1014 | object, do:: |
|
1014 | 1015 | |
|
1015 | 1016 | %gui wx |
|
1016 | 1017 | |
|
1017 | 1018 | For information on IPython's matplotlib_ integration (and the ``matplotlib`` |
|
1018 | 1019 | mode) see :ref:`this section <matplotlib_support>`. |
|
1019 | 1020 | |
|
1020 | 1021 | For developers that want to use IPython's GUI event loop integration in the |
|
1021 | 1022 | form of a library, these capabilities are exposed in library form in the |
|
1022 | 1023 | :mod:`IPython.lib.inputhook` and :mod:`IPython.lib.guisupport` modules. |
|
1023 | 1024 | Interested developers should see the module docstrings for more information, |
|
1024 | 1025 | but there are a few points that should be mentioned here. |
|
1025 | 1026 | |
|
1026 | 1027 | First, the ``PyOSInputHook`` approach only works in command line settings |
|
1027 | 1028 | where readline is activated. The integration with various eventloops |
|
1028 | 1029 | is handled somewhat differently (and more simply) when using the standalone |
|
1029 | 1030 | kernel, as in the qtconsole and notebook. |
|
1030 | 1031 | |
|
1031 | 1032 | Second, when using the ``PyOSInputHook`` approach, a GUI application should |
|
1032 | 1033 | *not* start its event loop. Instead all of this is handled by the |
|
1033 | 1034 | ``PyOSInputHook``. This means that applications that are meant to be used both |
|
1034 | 1035 | in IPython and as standalone apps need to have special code to detects how the |
|
1035 | 1036 | application is being run. We highly recommend using IPython's support for this. |
|
1036 | 1037 | Since the details vary slightly between toolkits, we point you to the various |
|
1037 | 1038 | examples in our source directory :file:`examples/lib` that demonstrate |
|
1038 | 1039 | these capabilities. |
|
1039 | 1040 | |
|
1040 | 1041 | Third, unlike previous versions of IPython, we no longer "hijack" (replace |
|
1041 | 1042 | them with no-ops) the event loops. This is done to allow applications that |
|
1042 | 1043 | actually need to run the real event loops to do so. This is often needed to |
|
1043 | 1044 | process pending events at critical points. |
|
1044 | 1045 | |
|
1045 | 1046 | Finally, we also have a number of examples in our source directory |
|
1046 | 1047 | :file:`examples/lib` that demonstrate these capabilities. |
|
1047 | 1048 | |
|
1048 | 1049 | PyQt and PySide |
|
1049 | 1050 | --------------- |
|
1050 | 1051 | |
|
1051 | 1052 | .. attempt at explanation of the complete mess that is Qt support |
|
1052 | 1053 | |
|
1053 | 1054 | When you use ``--gui=qt`` or ``--matplotlib=qt``, IPython can work with either |
|
1054 | 1055 | PyQt4 or PySide. There are three options for configuration here, because |
|
1055 | 1056 | PyQt4 has two APIs for QString and QVariant - v1, which is the default on |
|
1056 | 1057 | Python 2, and the more natural v2, which is the only API supported by PySide. |
|
1057 | 1058 | v2 is also the default for PyQt4 on Python 3. IPython's code for the QtConsole |
|
1058 | 1059 | uses v2, but you can still use any interface in your code, since the |
|
1059 | 1060 | Qt frontend is in a different process. |
|
1060 | 1061 | |
|
1061 | 1062 | The default will be to import PyQt4 without configuration of the APIs, thus |
|
1062 | 1063 | matching what most applications would expect. It will fall back of PySide if |
|
1063 | 1064 | PyQt4 is unavailable. |
|
1064 | 1065 | |
|
1065 | 1066 | If specified, IPython will respect the environment variable ``QT_API`` used |
|
1066 | 1067 | by ETS. ETS 4.0 also works with both PyQt4 and PySide, but it requires |
|
1067 | 1068 | PyQt4 to use its v2 API. So if ``QT_API=pyside`` PySide will be used, |
|
1068 | 1069 | and if ``QT_API=pyqt`` then PyQt4 will be used *with the v2 API* for |
|
1069 | 1070 | QString and QVariant, so ETS codes like MayaVi will also work with IPython. |
|
1070 | 1071 | |
|
1071 | 1072 | If you launch IPython in matplotlib mode with ``ipython --matplotlib=qt``, |
|
1072 | 1073 | then IPython will ask matplotlib which Qt library to use (only if QT_API is |
|
1073 | 1074 | *not set*), via the 'backend.qt4' rcParam. If matplotlib is version 1.0.1 or |
|
1074 | 1075 | older, then IPython will always use PyQt4 without setting the v2 APIs, since |
|
1075 | 1076 | neither v2 PyQt nor PySide work. |
|
1076 | 1077 | |
|
1077 | 1078 | .. warning:: |
|
1078 | 1079 | |
|
1079 | 1080 | Note that this means for ETS 4 to work with PyQt4, ``QT_API`` *must* be set |
|
1080 | 1081 | to work with IPython's qt integration, because otherwise PyQt4 will be |
|
1081 | 1082 | loaded in an incompatible mode. |
|
1082 | 1083 | |
|
1083 | 1084 | It also means that you must *not* have ``QT_API`` set if you want to |
|
1084 | 1085 | use ``--gui=qt`` with code that requires PyQt4 API v1. |
|
1085 | 1086 | |
|
1086 | 1087 | |
|
1087 | 1088 | .. _matplotlib_support: |
|
1088 | 1089 | |
|
1089 | 1090 | Plotting with matplotlib |
|
1090 | 1091 | ======================== |
|
1091 | 1092 | |
|
1092 | 1093 | matplotlib_ provides high quality 2D and 3D plotting for Python. matplotlib_ |
|
1093 | 1094 | can produce plots on screen using a variety of GUI toolkits, including Tk, |
|
1094 | 1095 | PyGTK, PyQt4 and wxPython. It also provides a number of commands useful for |
|
1095 | 1096 | scientific computing, all with a syntax compatible with that of the popular |
|
1096 | 1097 | Matlab program. |
|
1097 | 1098 | |
|
1098 | 1099 | To start IPython with matplotlib support, use the ``--matplotlib`` switch. If |
|
1099 | 1100 | IPython is already running, you can run the ``%matplotlib`` magic. If no |
|
1100 | 1101 | arguments are given, IPython will automatically detect your choice of |
|
1101 | 1102 | matplotlib backend. You can also request a specific backend with |
|
1102 | 1103 | ``%matplotlib backend``, where ``backend`` must be one of: 'tk', 'qt', 'wx', |
|
1103 | 1104 | 'gtk', 'osx'. In the web notebook and Qt console, 'inline' is also a valid |
|
1104 | 1105 | backend value, which produces static figures inlined inside the application |
|
1105 | 1106 | window instead of matplotlib's interactive figures that live in separate |
|
1106 | 1107 | windows. |
|
1107 | 1108 | |
|
1108 | 1109 | .. _interactive_demos: |
|
1109 | 1110 | |
|
1110 | 1111 | Interactive demos with IPython |
|
1111 | 1112 | ============================== |
|
1112 | 1113 | |
|
1113 | 1114 | IPython ships with a basic system for running scripts interactively in |
|
1114 | 1115 | sections, useful when presenting code to audiences. A few tags embedded |
|
1115 | 1116 | in comments (so that the script remains valid Python code) divide a file |
|
1116 | 1117 | into separate blocks, and the demo can be run one block at a time, with |
|
1117 | 1118 | IPython printing (with syntax highlighting) the block before executing |
|
1118 | 1119 | it, and returning to the interactive prompt after each block. The |
|
1119 | 1120 | interactive namespace is updated after each block is run with the |
|
1120 | 1121 | contents of the demo's namespace. |
|
1121 | 1122 | |
|
1122 | 1123 | This allows you to show a piece of code, run it and then execute |
|
1123 | 1124 | interactively commands based on the variables just created. Once you |
|
1124 | 1125 | want to continue, you simply execute the next block of the demo. The |
|
1125 | 1126 | following listing shows the markup necessary for dividing a script into |
|
1126 | 1127 | sections for execution as a demo: |
|
1127 | 1128 | |
|
1128 | 1129 | .. literalinclude:: ../../../examples/lib/example-demo.py |
|
1129 | 1130 | :language: python |
|
1130 | 1131 | |
|
1131 | 1132 | In order to run a file as a demo, you must first make a Demo object out |
|
1132 | 1133 | of it. If the file is named myscript.py, the following code will make a |
|
1133 | 1134 | demo:: |
|
1134 | 1135 | |
|
1135 | 1136 | from IPython.lib.demo import Demo |
|
1136 | 1137 | |
|
1137 | 1138 | mydemo = Demo('myscript.py') |
|
1138 | 1139 | |
|
1139 | 1140 | This creates the mydemo object, whose blocks you run one at a time by |
|
1140 | 1141 | simply calling the object with no arguments. If you have autocall active |
|
1141 | 1142 | in IPython (the default), all you need to do is type:: |
|
1142 | 1143 | |
|
1143 | 1144 | mydemo |
|
1144 | 1145 | |
|
1145 | 1146 | and IPython will call it, executing each block. Demo objects can be |
|
1146 | 1147 | restarted, you can move forward or back skipping blocks, re-execute the |
|
1147 | 1148 | last block, etc. Simply use the Tab key on a demo object to see its |
|
1148 | 1149 | methods, and call '?' on them to see their docstrings for more usage |
|
1149 | 1150 | details. In addition, the demo module itself contains a comprehensive |
|
1150 | 1151 | docstring, which you can access via:: |
|
1151 | 1152 | |
|
1152 | 1153 | from IPython.lib import demo |
|
1153 | 1154 | |
|
1154 | 1155 | demo? |
|
1155 | 1156 | |
|
1156 | 1157 | Limitations: It is important to note that these demos are limited to |
|
1157 | 1158 | fairly simple uses. In particular, you cannot break up sections within |
|
1158 | 1159 | indented code (loops, if statements, function definitions, etc.) |
|
1159 | 1160 | Supporting something like this would basically require tracking the |
|
1160 | 1161 | internal execution state of the Python interpreter, so only top-level |
|
1161 | 1162 | divisions are allowed. If you want to be able to open an IPython |
|
1162 | 1163 | instance at an arbitrary point in a program, you can use IPython's |
|
1163 | 1164 | embedding facilities, see :func:`IPython.embed` for details. |
|
1164 | 1165 | |
|
1165 | 1166 | .. include:: ../links.txt |
@@ -1,102 +1,102 | |||
|
1 | 1 | .. _tips: |
|
2 | 2 | |
|
3 | 3 | ===================== |
|
4 | 4 | IPython Tips & Tricks |
|
5 | 5 | ===================== |
|
6 | 6 | |
|
7 | 7 | The `IPython cookbook |
|
8 | 8 | <https://github.com/ipython/ipython/wiki?path=Cookbook>`_ details more things |
|
9 | 9 | you can do with IPython. |
|
10 | 10 | |
|
11 | 11 | .. This is not in the current version: |
|
12 | 12 | |
|
13 | 13 | |
|
14 | 14 | Embed IPython in your programs |
|
15 | 15 | ------------------------------ |
|
16 | 16 | |
|
17 | 17 | A few lines of code are enough to load a complete IPython inside your own |
|
18 | 18 | programs, giving you the ability to work with your data interactively after |
|
19 | 19 | automatic processing has been completed. See :ref:`the embedding section <embedding>`. |
|
20 | 20 | |
|
21 | 21 | Run doctests |
|
22 | 22 | ------------ |
|
23 | 23 | |
|
24 | 24 | Run your doctests from within IPython for development and debugging. The |
|
25 | 25 | special %doctest_mode command toggles a mode where the prompt, output and |
|
26 | 26 | exceptions display matches as closely as possible that of the default Python |
|
27 | 27 | interpreter. In addition, this mode allows you to directly paste in code that |
|
28 | 28 | contains leading '>>>' prompts, even if they have extra leading whitespace |
|
29 | 29 | (as is common in doctest files). This combined with the ``%history -t`` call |
|
30 | 30 | to see your translated history allows for an easy doctest workflow, where you |
|
31 | 31 | can go from doctest to interactive execution to pasting into valid Python code |
|
32 | 32 | as needed. |
|
33 | 33 | |
|
34 | 34 | Use IPython to present interactive demos |
|
35 | 35 | ---------------------------------------- |
|
36 | 36 | |
|
37 | 37 | Use the :class:`IPython.lib.demo.Demo` class to load any Python script as an interactive |
|
38 | 38 | demo. With a minimal amount of simple markup, you can control the execution of |
|
39 | 39 | the script, stopping as needed. See :ref:`here <interactive_demos>` for more. |
|
40 | 40 | |
|
41 | 41 | Suppress output |
|
42 | 42 | --------------- |
|
43 | 43 | |
|
44 | 44 | Put a ';' at the end of a line to suppress the printing of output. This is |
|
45 | 45 | useful when doing calculations which generate long output you are not |
|
46 | 46 | interested in seeing. It also keeps the object out of the output cache, so if |
|
47 | 47 | you're working with large temporary objects, they'll be released from memory sooner. |
|
48 | 48 | |
|
49 | 49 | Lightweight 'version control' |
|
50 | 50 | ----------------------------- |
|
51 | 51 | |
|
52 | 52 | When you call ``%edit`` with no arguments, IPython opens an empty editor |
|
53 | 53 | with a temporary file, and it returns the contents of your editing |
|
54 | 54 | session as a string variable. Thanks to IPython's output caching |
|
55 | 55 | mechanism, this is automatically stored:: |
|
56 | 56 | |
|
57 | 57 | In [1]: %edit |
|
58 | 58 | |
|
59 | 59 | IPython will make a temporary file named: /tmp/ipython_edit_yR-HCN.py |
|
60 | 60 | |
|
61 | 61 | Editing... done. Executing edited code... |
|
62 | 62 | |
|
63 | 63 | hello - this is a temporary file |
|
64 | 64 | |
|
65 |
Out[1]: "print |
|
|
65 | Out[1]: "print('hello - this is a temporary file')\n" | |
|
66 | 66 | |
|
67 | 67 | Now, if you call ``%edit -p``, IPython tries to open an editor with the |
|
68 | 68 | same data as the last time you used %edit. So if you haven't used %edit |
|
69 | 69 | in the meantime, this same contents will reopen; however, it will be |
|
70 | 70 | done in a new file. This means that if you make changes and you later |
|
71 | 71 | want to find an old version, you can always retrieve it by using its |
|
72 | 72 | output number, via '%edit _NN', where NN is the number of the output |
|
73 | 73 | prompt. |
|
74 | 74 | |
|
75 | 75 | Continuing with the example above, this should illustrate this idea:: |
|
76 | 76 | |
|
77 | 77 | In [2]: edit -p |
|
78 | 78 | |
|
79 | 79 | IPython will make a temporary file named: /tmp/ipython_edit_nA09Qk.py |
|
80 | 80 | |
|
81 | 81 | Editing... done. Executing edited code... |
|
82 | 82 | |
|
83 | 83 | hello - now I made some changes |
|
84 | 84 | |
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85 |
Out[2]: "print |
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85 | Out[2]: "print('hello - now I made some changes')\n" | |
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86 | 86 | |
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87 | 87 | In [3]: edit _1 |
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88 | 88 | |
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89 | 89 | IPython will make a temporary file named: /tmp/ipython_edit_gy6-zD.py |
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90 | 90 | |
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91 | 91 | Editing... done. Executing edited code... |
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92 | 92 | |
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93 | 93 | hello - this is a temporary file |
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94 | 94 | |
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95 | 95 | IPython version control at work :) |
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96 | 96 | |
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97 |
Out[3]: "print |
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97 | Out[3]: "print('hello - this is a temporary file')\nprint('IPython version control at work :)')\n" | |
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98 | 98 | |
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99 | 99 | |
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100 | 100 | This section was written after a contribution by Alexander Belchenko on |
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101 | 101 | the IPython user list. |
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102 | 102 |
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