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1 | 1 | .. _parallel_magics: |
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2 | 2 | |
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3 | 3 | ======================= |
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4 | 4 | Parallel Magic Commands |
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5 | 5 | ======================= |
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6 | 6 | |
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7 | 7 | We provide a few IPython magic commands |
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8 | 8 | that make it a bit more pleasant to execute Python commands on the engines interactively. |
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9 | 9 | These are mainly shortcuts to :meth:`.DirectView.execute` |
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10 | 10 | and :meth:`.AsyncResult.display_outputs` methods respectively. |
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11 | 11 | |
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12 | 12 | These magics will automatically become available when you create a Client: |
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13 | 13 | |
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14 | 14 | .. sourcecode:: ipython |
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15 | 15 | |
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16 |
In [ |
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16 | In [1]: from IPython.parallel import Client | |
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17 | In [2]: rc = Client() | |
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17 | 18 | |
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18 | 19 | The initially active View will have attributes ``targets='all', block=True``, |
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19 | 20 | which is a blocking view of all engines, evaluated at request time |
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20 | 21 | (adding/removing engines will change where this view's tasks will run). |
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21 | 22 | |
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22 | 23 | The Magics |
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23 | 24 | ========== |
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24 | 25 | |
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25 | 26 | %px |
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26 | 27 | --- |
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27 | 28 | |
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28 | 29 | The %px magic executes a single Python command on the engines |
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29 | 30 | specified by the :attr:`targets` attribute of the :class:`DirectView` instance: |
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30 | 31 | |
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31 | 32 | .. sourcecode:: ipython |
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32 | 33 | |
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33 | 34 | # import numpy here and everywhere |
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34 | 35 | In [25]: with rc[:].sync_imports(): |
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35 | 36 | ....: import numpy |
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36 | 37 | importing numpy on engine(s) |
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37 | 38 | |
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38 | 39 | In [27]: %px a = numpy.random.rand(2,2) |
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39 | 40 | Parallel execution on engines: [0, 1, 2, 3] |
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40 | 41 | |
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41 | 42 | In [28]: %px numpy.linalg.eigvals(a) |
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42 | 43 | Parallel execution on engines: [0, 1, 2, 3] |
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43 | 44 | Out [0:68]: array([ 0.77120707, -0.19448286]) |
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44 | 45 | Out [1:68]: array([ 1.10815921, 0.05110369]) |
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45 | 46 | Out [2:68]: array([ 0.74625527, -0.37475081]) |
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46 | 47 | Out [3:68]: array([ 0.72931905, 0.07159743]) |
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47 | 48 | |
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48 | 49 | In [29]: %px print 'hi' |
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49 | 50 | Parallel execution on engine(s): all |
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50 | 51 | [stdout:0] hi |
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51 | 52 | [stdout:1] hi |
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52 | 53 | [stdout:2] hi |
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53 | 54 | [stdout:3] hi |
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54 | 55 | |
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55 | 56 | |
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56 | 57 | Since engines are IPython as well, you can even run magics remotely: |
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57 | 58 | |
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58 | 59 | .. sourcecode:: ipython |
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59 | 60 | |
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60 | 61 | In [28]: %px %pylab inline |
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61 | 62 | Parallel execution on engine(s): all |
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62 | 63 | [stdout:0] |
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63 | 64 | Populating the interactive namespace from numpy and matplotlib |
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64 | 65 | [stdout:1] |
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65 | 66 | Populating the interactive namespace from numpy and matplotlib |
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66 | 67 | [stdout:2] |
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67 | 68 | Populating the interactive namespace from numpy and matplotlib |
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68 | 69 | [stdout:3] |
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69 | 70 | Populating the interactive namespace from numpy and matplotlib |
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70 | 71 | |
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71 | 72 | And once in pylab mode with the inline backend, |
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72 | 73 | you can make plots and they will be displayed in your frontend |
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73 | 74 | if it supports the inline figures (e.g. notebook or qtconsole): |
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74 | 75 | |
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75 | 76 | .. sourcecode:: ipython |
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76 | 77 | |
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77 | 78 | In [40]: %px plot(rand(100)) |
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78 | 79 | Parallel execution on engine(s): all |
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79 | 80 | <plot0> |
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80 | 81 | <plot1> |
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81 | 82 | <plot2> |
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82 | 83 | <plot3> |
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83 | 84 | Out[0:79]: [<matplotlib.lines.Line2D at 0x10a6286d0>] |
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84 | 85 | Out[1:79]: [<matplotlib.lines.Line2D at 0x10b9476d0>] |
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85 | 86 | Out[2:79]: [<matplotlib.lines.Line2D at 0x110652750>] |
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86 | 87 | Out[3:79]: [<matplotlib.lines.Line2D at 0x10c6566d0>] |
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87 | 88 | |
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88 | 89 | |
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89 | 90 | %%px Cell Magic |
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90 | 91 | --------------- |
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91 | 92 | |
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92 | 93 | %%px can be used as a Cell Magic, which accepts some arguments for controlling |
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93 | 94 | the execution. |
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94 | 95 | |
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95 | 96 | |
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96 | 97 | Targets and Blocking |
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97 | 98 | ******************** |
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98 | 99 | |
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99 | 100 | %%px accepts ``--targets`` for controlling which engines on which to run, |
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100 | 101 | and ``--[no]block`` for specifying the blocking behavior of this cell, |
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101 | 102 | independent of the defaults for the View. |
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102 | 103 | |
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103 | 104 | .. sourcecode:: ipython |
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104 | 105 | |
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105 | 106 | In [6]: %%px --targets ::2 |
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106 | 107 | ...: print "I am even" |
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107 | 108 | ...: |
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108 | 109 | Parallel execution on engine(s): [0, 2] |
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109 | 110 | [stdout:0] I am even |
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110 | 111 | [stdout:2] I am even |
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111 | 112 | |
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112 | 113 | In [7]: %%px --targets 1 |
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113 | 114 | ...: print "I am number 1" |
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114 | 115 | ...: |
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115 | 116 | Parallel execution on engine(s): 1 |
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116 | 117 | I am number 1 |
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117 | 118 | |
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118 | 119 | In [8]: %%px |
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119 | 120 | ...: print "still 'all' by default" |
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120 | 121 | ...: |
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121 | 122 | Parallel execution on engine(s): all |
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122 | 123 | [stdout:0] still 'all' by default |
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123 | 124 | [stdout:1] still 'all' by default |
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124 | 125 | [stdout:2] still 'all' by default |
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125 | 126 | [stdout:3] still 'all' by default |
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126 | 127 | |
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127 | 128 | In [9]: %%px --noblock |
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128 | 129 | ...: import time |
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129 | 130 | ...: time.sleep(1) |
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130 | 131 | ...: time.time() |
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131 | 132 | ...: |
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132 | 133 | Async parallel execution on engine(s): all |
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133 | 134 | Out[9]: <AsyncResult: execute> |
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134 | 135 | |
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135 | 136 | In [10]: %pxresult |
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136 | 137 | Out[0:12]: 1339454561.069116 |
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137 | 138 | Out[1:10]: 1339454561.076752 |
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138 | 139 | Out[2:12]: 1339454561.072837 |
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139 | 140 | Out[3:10]: 1339454561.066665 |
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140 | 141 | |
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141 | 142 | |
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142 | 143 | .. seealso:: |
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143 | 144 | |
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144 | 145 | :ref:`pxconfig` accepts these same arguments for changing the *default* |
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145 | 146 | values of targets/blocking for the active View. |
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146 | 147 | |
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147 | 148 | |
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148 | 149 | Output Display |
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149 | 150 | ************** |
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150 | 151 | |
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151 | 152 | |
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152 | 153 | %%px also accepts a ``--group-outputs`` argument, |
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153 | 154 | which adjusts how the outputs of multiple engines are presented. |
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154 | 155 | |
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155 | 156 | .. seealso:: |
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156 | 157 | |
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157 | 158 | :meth:`.AsyncResult.display_outputs` for the grouping options. |
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158 | 159 | |
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159 | 160 | .. sourcecode:: ipython |
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160 | 161 | |
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161 | 162 | In [50]: %%px --block --group-outputs=engine |
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162 | 163 | ....: import numpy as np |
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163 | 164 | ....: A = np.random.random((2,2)) |
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164 | 165 | ....: ev = numpy.linalg.eigvals(A) |
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165 | 166 | ....: print ev |
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166 | 167 | ....: ev.max() |
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167 | 168 | ....: |
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168 | 169 | Parallel execution on engine(s): all |
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169 | 170 | [stdout:0] [ 0.60640442 0.95919621] |
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170 | 171 | Out [0:73]: 0.9591962130899806 |
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171 | 172 | [stdout:1] [ 0.38501813 1.29430871] |
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172 | 173 | Out [1:73]: 1.2943087091452372 |
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173 | 174 | [stdout:2] [-0.85925141 0.9387692 ] |
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174 | 175 | Out [2:73]: 0.93876920456230284 |
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175 | 176 | [stdout:3] [ 0.37998269 1.24218246] |
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176 | 177 | Out [3:73]: 1.2421824618493817 |
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177 | 178 | |
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178 | 179 | |
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179 | 180 | %pxresult |
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180 | 181 | --------- |
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181 | 182 | |
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182 | 183 | If you are using %px in non-blocking mode, you won't get output. |
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183 | 184 | You can use %pxresult to display the outputs of the latest command, |
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184 | 185 | just as is done when %px is blocking: |
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185 | 186 | |
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186 | 187 | .. sourcecode:: ipython |
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187 | 188 | |
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188 | 189 | In [39]: dv.block = False |
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189 | 190 | |
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190 | 191 | In [40]: %px print 'hi' |
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191 | 192 | Async parallel execution on engine(s): all |
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192 | 193 | |
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193 | 194 | In [41]: %pxresult |
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194 | 195 | [stdout:0] hi |
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195 | 196 | [stdout:1] hi |
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196 | 197 | [stdout:2] hi |
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197 | 198 | [stdout:3] hi |
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198 | 199 | |
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199 | 200 | %pxresult simply calls :meth:`.AsyncResult.display_outputs` on the most recent request. |
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200 | 201 | It accepts the same output-grouping arguments as %%px, so you can use it to view |
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201 | 202 | a result in different ways. |
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202 | 203 | |
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203 | 204 | |
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204 | 205 | %autopx |
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205 | 206 | ------- |
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206 | 207 | |
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207 | 208 | The %autopx magic switches to a mode where everything you type is executed |
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208 | 209 | on the engines until you do %autopx again. |
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209 | 210 | |
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210 | 211 | .. sourcecode:: ipython |
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211 | 212 | |
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212 | 213 | In [30]: dv.block=True |
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213 | 214 | |
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214 | 215 | In [31]: %autopx |
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215 | 216 | %autopx enabled |
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216 | 217 | |
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217 | 218 | In [32]: max_evals = [] |
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218 | 219 | |
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219 | 220 | In [33]: for i in range(100): |
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220 | 221 | ....: a = numpy.random.rand(10,10) |
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221 | 222 | ....: a = a+a.transpose() |
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222 | 223 | ....: evals = numpy.linalg.eigvals(a) |
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223 | 224 | ....: max_evals.append(evals[0].real) |
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224 | 225 | ....: |
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225 | 226 | |
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226 | 227 | In [34]: print "Average max eigenvalue is: %f" % (sum(max_evals)/len(max_evals)) |
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227 | 228 | [stdout:0] Average max eigenvalue is: 10.193101 |
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228 | 229 | [stdout:1] Average max eigenvalue is: 10.064508 |
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229 | 230 | [stdout:2] Average max eigenvalue is: 10.055724 |
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230 | 231 | [stdout:3] Average max eigenvalue is: 10.086876 |
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231 | 232 | |
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232 | 233 | In [35]: %autopx |
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233 | 234 | Auto Parallel Disabled |
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234 | 235 | |
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235 | 236 | .. _pxconfig: |
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236 | 237 | |
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237 | 238 | %pxconfig |
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238 | 239 | --------- |
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239 | 240 | |
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240 | 241 | The default targets and blocking behavior for the magics are governed by the :attr:`block` |
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241 | 242 | and :attr:`targets` attribute of the active View. If you have a handle for the view, |
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242 | 243 | you can set these attributes directly, but if you don't, you can change them with |
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243 | 244 | the %pxconfig magic: |
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244 | 245 | |
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245 | 246 | .. sourcecode:: ipython |
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246 | 247 | |
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247 | 248 | In [3]: %pxconfig --block |
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248 | 249 | |
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249 | 250 | In [5]: %px print 'hi' |
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250 | 251 | Parallel execution on engine(s): all |
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251 | 252 | [stdout:0] hi |
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252 | 253 | [stdout:1] hi |
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253 | 254 | [stdout:2] hi |
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254 | 255 | [stdout:3] hi |
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255 | 256 | |
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256 | 257 | In [6]: %pxconfig --targets ::2 |
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257 | 258 | |
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258 | 259 | In [7]: %px print 'hi' |
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259 | 260 | Parallel execution on engine(s): [0, 2] |
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260 | 261 | [stdout:0] hi |
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261 | 262 | [stdout:2] hi |
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262 | 263 | |
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263 | 264 | In [8]: %pxconfig --noblock |
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264 | 265 | |
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265 | 266 | In [9]: %px print 'are you there?' |
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266 | 267 | Async parallel execution on engine(s): [0, 2] |
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267 | 268 | Out[9]: <AsyncResult: execute> |
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268 | 269 | |
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269 | 270 | In [10]: %pxresult |
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270 | 271 | [stdout:0] are you there? |
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271 | 272 | [stdout:2] are you there? |
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272 | 273 | |
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273 | 274 | |
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274 | 275 | Multiple Active Views |
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275 | 276 | ===================== |
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276 | 277 | |
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277 | 278 | The parallel magics are associated with a particular :class:`~.DirectView` object. |
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278 | 279 | You can change the active view by calling the :meth:`~.DirectView.activate` method |
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279 | 280 | on any view. |
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280 | 281 | |
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281 | 282 | .. sourcecode:: ipython |
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282 | 283 | |
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283 | 284 | In [11]: even = rc[::2] |
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284 | 285 | |
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285 | 286 | In [12]: even.activate() |
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286 | 287 | |
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287 | 288 | In [13]: %px print 'hi' |
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288 | 289 | Async parallel execution on engine(s): [0, 2] |
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289 | 290 | Out[13]: <AsyncResult: execute> |
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290 | 291 | |
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291 | 292 | In [14]: even.block = True |
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292 | 293 | |
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293 | 294 | In [15]: %px print 'hi' |
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294 | 295 | Parallel execution on engine(s): [0, 2] |
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295 | 296 | [stdout:0] hi |
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296 | 297 | [stdout:2] hi |
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297 | 298 | |
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298 | 299 | When activating a View, you can also specify a *suffix*, so that a whole different |
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299 | 300 | set of magics are associated with that view, without replacing the existing ones. |
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300 | 301 | |
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301 | 302 | .. sourcecode:: ipython |
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302 | 303 | |
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303 | 304 | # restore the original DirecView to the base %px magics |
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304 | 305 | In [16]: rc.activate() |
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305 | 306 | Out[16]: <DirectView all> |
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306 | 307 | |
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307 | 308 | In [17]: even.activate('_even') |
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308 | 309 | |
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309 | 310 | In [18]: %px print 'hi all' |
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310 | 311 | Parallel execution on engine(s): all |
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311 | 312 | [stdout:0] hi all |
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312 | 313 | [stdout:1] hi all |
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313 | 314 | [stdout:2] hi all |
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314 | 315 | [stdout:3] hi all |
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315 | 316 | |
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316 | 317 | In [19]: %px_even print "We aren't odd!" |
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317 | 318 | Parallel execution on engine(s): [0, 2] |
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318 | 319 | [stdout:0] We aren't odd! |
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319 | 320 | [stdout:2] We aren't odd! |
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320 | 321 | |
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321 | 322 | This suffix is applied to the end of all magics, e.g. %autopx_even, %pxresult_even, etc. |
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322 | 323 | |
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323 | 324 | For convenience, the :class:`~.Client` has a :meth:`~.Client.activate` method as well, |
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324 | 325 | which creates a DirectView with block=True, activates it, and returns the new View. |
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325 | 326 | |
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326 | 327 | The initial magics registered when you create a client are the result of a call to |
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327 | 328 | :meth:`rc.activate` with default args. |
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328 | 329 | |
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329 | 330 | |
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330 | 331 | Engines as Kernels |
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331 | 332 | ================== |
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332 | 333 | |
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333 | 334 | Engines are really the same object as the Kernels used elsewhere in IPython, |
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334 | 335 | with the minor exception that engines connect to a controller, while regular kernels |
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335 | 336 | bind their sockets, listening for connections from a QtConsole or other frontends. |
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336 | 337 | |
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337 | 338 | Sometimes for debugging or inspection purposes, you would like a QtConsole connected |
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338 | 339 | to an engine for more direct interaction. You can do this by first instructing |
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339 | 340 | the Engine to *also* bind its kernel, to listen for connections: |
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340 | 341 | |
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341 | 342 | .. sourcecode:: ipython |
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342 | 343 | |
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343 | 344 | In [50]: %px from IPython.parallel import bind_kernel; bind_kernel() |
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344 | 345 | |
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345 | 346 | Then, if your engines are local, you can start a qtconsole right on the engine(s): |
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346 | 347 | |
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347 | 348 | .. sourcecode:: ipython |
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348 | 349 | |
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349 | 350 | In [51]: %px %qtconsole |
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350 | 351 | |
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351 | 352 | Careful with this one, because if your view is of 16 engines it will start 16 QtConsoles! |
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352 | 353 | |
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353 | 354 | Or you can view just the connection info, and work out the right way to connect to the engines, |
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354 | 355 | depending on where they live and where you are: |
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355 | 356 | |
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356 | 357 | .. sourcecode:: ipython |
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357 | 358 | |
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358 | 359 | In [51]: %px %connect_info |
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359 | 360 | Parallel execution on engine(s): all |
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360 | 361 | [stdout:0] |
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361 | 362 | { |
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362 | 363 | "stdin_port": 60387, |
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363 | 364 | "ip": "127.0.0.1", |
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364 | 365 | "hb_port": 50835, |
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365 | 366 | "key": "eee2dd69-7dd3-4340-bf3e-7e2e22a62542", |
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366 | 367 | "shell_port": 55328, |
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367 | 368 | "iopub_port": 58264 |
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368 | 369 | } |
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369 | 370 | |
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370 | 371 | Paste the above JSON into a file, and connect with: |
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371 | 372 | $> ipython <app> --existing <file> |
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372 | 373 | or, if you are local, you can connect with just: |
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373 | 374 | $> ipython <app> --existing kernel-60125.json |
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374 | 375 | or even just: |
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375 | 376 | $> ipython <app> --existing |
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376 | 377 | if this is the most recent IPython session you have started. |
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377 | 378 | [stdout:1] |
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378 | 379 | { |
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379 | 380 | "stdin_port": 61869, |
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380 | 381 | ... |
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381 | 382 | |
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382 | 383 | .. note:: |
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383 | 384 | |
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384 | 385 | ``%qtconsole`` will call :func:`bind_kernel` on an engine if it hasn't been done already, |
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385 | 386 | so you can often skip that first step. |
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386 | 387 | |
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387 | 388 |
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