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1 =================
1 =================
2 Python vs IPython
2 Python vs IPython
3 =================
3 =================
4
4
5 This document is meant to highlight the main differences between the Python
5 This document is meant to highlight the main differences between the Python
6 language and what are the specific construct you can do only in IPython.
6 language and what are the specific construct you can do only in IPython.
7
7
8 Unless expressed otherwise all of the construct you will see here will raise a
8 Unless expressed otherwise all of the construct you will see here will raise a
9 ``SyntaxError`` if run in a pure Python shell, or if executing in a Python
9 ``SyntaxError`` if run in a pure Python shell, or if executing in a Python
10 script.
10 script.
11
11
12 Each of these features are describe more in details in further part of the documentation.
12 Each of these features are describe more in details in further part of the documentation.
13
13
14
14
15 Quick overview:
15 Quick overview:
16 ===============
16 ===============
17
17
18
18
19 All the following construct are valid IPython syntax:
19 All the following construct are valid IPython syntax:
20
20
21 .. code-block:: ipython
21 .. code-block:: ipython
22
22
23 In [1]: ?
23 In [1]: ?
24
24
25 .. code-block:: ipython
25 .. code-block:: ipython
26
26
27 In [1]: ?object
27 In [1]: ?object
28
28
29
29
30 .. code-block:: ipython
30 .. code-block:: ipython
31
31
32 In [1]: object?
32 In [1]: object?
33
33
34 .. code-block:: ipython
34 .. code-block:: ipython
35
35
36 In [1]: *pattern*?
36 In [1]: *pattern*?
37
37
38 .. code-block:: ipython
38 .. code-block:: ipython
39
39
40 In [1]: %shell like --syntax
40 In [1]: %shell like --syntax
41
41
42 .. code-block:: ipython
42 .. code-block:: ipython
43
43
44 In [1]: !ls
44 In [1]: !ls
45
45
46 .. code-block:: ipython
46 .. code-block:: ipython
47
47
48 In [1]: my_files =! ls ~/
48 In [1]: my_files = !ls ~/
49 In [1]: for i,file in enumerate(my_file):
49 In [1]: for i,file in enumerate(my_file):
50 ...: raw = !echo $file
50 ...: raw = !echo $file
51 ...: !echo {files[0].upper()} $raw
51 ...: !echo {files[0].upper()} $raw
52
52
53
53
54 .. code-block:: ipython
54 .. code-block:: ipython
55
55
56 In [1]: %%perl magic --function
56 In [1]: %%perl magic --function
57 ...: @months = ("July", "August", "September");
57 ...: @months = ("July", "August", "September");
58 ...: print $months[0];
58 ...: print $months[0];
59
59
60
60
61 Each of these construct is compile by IPython into valid python code and will
61 Each of these construct is compile by IPython into valid python code and will
62 do most of the time what you expect it will do. Let see each of these example
62 do most of the time what you expect it will do. Let see each of these example
63 in more detail.
63 in more detail.
64
64
65
65
66 Accessing help
66 Accessing help
67 ==============
67 ==============
68
68
69 As IPython is mostly an interactive shell, the question mark is a simple
69 As IPython is mostly an interactive shell, the question mark is a simple
70 shortcut to get help. A question mark alone will bring up the IPython help:
70 shortcut to get help. A question mark alone will bring up the IPython help:
71
71
72 .. code-block:: ipython
72 .. code-block:: ipython
73
73
74 In [1]: ?
74 In [1]: ?
75
75
76 IPython -- An enhanced Interactive Python
76 IPython -- An enhanced Interactive Python
77 =========================================
77 =========================================
78
78
79 IPython offers a combination of convenient shell features, special commands
79 IPython offers a combination of convenient shell features, special commands
80 and a history mechanism for both input (command history) and output (results
80 and a history mechanism for both input (command history) and output (results
81 caching, similar to Mathematica). It is intended to be a fully compatible
81 caching, similar to Mathematica). It is intended to be a fully compatible
82 replacement for the standard Python interpreter, while offering vastly
82 replacement for the standard Python interpreter, while offering vastly
83 improved functionality and flexibility.
83 improved functionality and flexibility.
84
84
85 At your system command line, type 'ipython -h' to see the command line
85 At your system command line, type 'ipython -h' to see the command line
86 options available. This document only describes interactive features.
86 options available. This document only describes interactive features.
87
87
88 MAIN FEATURES
88 MAIN FEATURES
89 -------------
89 -------------
90 ...
90 ...
91
91
92 A single question mark before, or after an object available in current
92 A single question mark before, or after an object available in current
93 namespace will show help relative to this object:
93 namespace will show help relative to this object:
94
94
95 .. code-block:: ipython
95 .. code-block:: ipython
96
96
97 In [6]: object?
97 In [6]: object?
98 Docstring: The most base type
98 Docstring: The most base type
99 Type: type
99 Type: type
100
100
101
101
102 A double question mark will try to pull out more information about the object,
102 A double question mark will try to pull out more information about the object,
103 and if possible display the python source code of this object.
103 and if possible display the python source code of this object.
104
104
105 .. code-block:: ipython
105 .. code-block:: ipython
106
106
107 In[1]: import collections
107 In[1]: import collections
108 In[2]: collection.Counter??
108 In[2]: collection.Counter??
109
109
110 Init signature: collections.Counter(*args, **kwds)
110 Init signature: collections.Counter(*args, **kwds)
111 Source:
111 Source:
112 class Counter(dict):
112 class Counter(dict):
113 '''Dict subclass for counting hashable items. Sometimes called a bag
113 '''Dict subclass for counting hashable items. Sometimes called a bag
114 or multiset. Elements are stored as dictionary keys and their counts
114 or multiset. Elements are stored as dictionary keys and their counts
115 are stored as dictionary values.
115 are stored as dictionary values.
116
116
117 >>> c = Counter('abcdeabcdabcaba') # count elements from a string
117 >>> c = Counter('abcdeabcdabcaba') # count elements from a string
118
118
119 >>> c.most_common(3) # three most common elements
119 >>> c.most_common(3) # three most common elements
120 [('a', 5), ('b', 4), ('c', 3)]
120 [('a', 5), ('b', 4), ('c', 3)]
121 >>> sorted(c) # list all unique elements
121 >>> sorted(c) # list all unique elements
122 ['a', 'b', 'c', 'd', 'e']
122 ['a', 'b', 'c', 'd', 'e']
123 >>> ''.join(sorted(c.elements())) # list elements with repetitions
123 >>> ''.join(sorted(c.elements())) # list elements with repetitions
124 'aaaaabbbbcccdde'
124 'aaaaabbbbcccdde'
125 ...
125 ...
126
126
127
127
128
128
129 If you are looking for an object, the use of wildcards ``*`` in conjunction
129 If you are looking for an object, the use of wildcards ``*`` in conjunction
130 with question mark will allow you to search current namespace for object with
130 with question mark will allow you to search current namespace for object with
131 matching names:
131 matching names:
132
132
133 .. code-block:: ipython
133 .. code-block:: ipython
134
134
135 In [24]: *int*?
135 In [24]: *int*?
136 FloatingPointError
136 FloatingPointError
137 int
137 int
138 print
138 print
139
139
140
140
141 Shell Assignment
141 Shell Assignment
142 ================
142 ================
143
143
144
144
145 When doing interactive computing it is common to need to access the underlying shell.
145 When doing interactive computing it is common to need to access the underlying shell.
146 This is doable through the use of the exclamation mark ``!`` (or bang).
146 This is doable through the use of the exclamation mark ``!`` (or bang).
147
147
148 This allow to execute simple command when present in beginning of line:
148 This allow to execute simple command when present in beginning of line:
149
149
150 .. code-block:: ipython
150 .. code-block:: ipython
151
151
152 In[1]: !pwd
152 In[1]: !pwd
153 /User/home/
153 /User/home/
154
154
155 Change directory:
155 Change directory:
156
156
157 .. code-block:: ipython
157 .. code-block:: ipython
158
158
159 In[1]: !cd /var/etc
159 In[1]: !cd /var/etc
160
160
161 Or edit file:
161 Or edit file:
162
162
163 .. code-block:: ipython
163 .. code-block:: ipython
164
164
165 In[1]: !mvim myfile.txt
165 In[1]: !mvim myfile.txt
166
166
167
167
168 The line after the bang can call any program installed in the underlying
168 The line after the bang can call any program installed in the underlying
169 shell, and support variable expansion in the form of ``$variable`` or ``{variable}``.
169 shell, and support variable expansion in the form of ``$variable`` or ``{variable}``.
170 The later form of expansion supports arbitrary python expression:
170 The later form of expansion supports arbitrary python expression:
171
171
172 .. code-block:: ipython
172 .. code-block:: ipython
173
173
174 In[1]: file = 'myfile.txt'
174 In[1]: file = 'myfile.txt'
175
175
176 In[2]: !mv $file {file.upper()}
176 In[2]: !mv $file {file.upper()}
177
177
178
178
179 The bang can also be present in the right hand side of an assignment, just
179 The bang can also be present in the right hand side of an assignment, just
180 after the equal sign, or separated from it by a white space. In which case the
180 after the equal sign, or separated from it by a white space. In which case the
181 standard output of the command after the bang ``!`` will be split out into lines
181 standard output of the command after the bang ``!`` will be split out into lines
182 in a list-like object and assign to the left hand side.
182 in a list-like object and assign to the left hand side.
183
183
184 This allow you for example to put the list of files of the current working directory in a variable:
184 This allow you for example to put the list of files of the current working directory in a variable:
185
185
186 .. code-block:: ipython
186 .. code-block:: ipython
187
187
188 In[1]: my_files != ls
188 In[1]: my_files = !ls
189
189
190
190
191 You can combine the different possibilities in for loops, condition, functions...:
191 You can combine the different possibilities in for loops, condition, functions...:
192
192
193 .. code-block:: ipython
193 .. code-block:: ipython
194
194
195 my_files =! ls ~/
195 my_files = !ls ~/
196 b = "backup file"
196 b = "backup file"
197 for i,file in enumerate(my_file):
197 for i,file in enumerate(my_file):
198 raw = !echo $backup $file
198 raw = !echo $backup $file
199 !cp $file {file.split('.')[0]+'.bak'}
199 !cp $file {file.split('.')[0]+'.bak'}
200
200
201
201
202 Magics
202 Magics
203 ------
203 ------
204
204
205 Magics function are often present in the form of shell-like syntax, but are
205 Magics function are often present in the form of shell-like syntax, but are
206 under the hood python function. The syntax and assignment possibility are
206 under the hood python function. The syntax and assignment possibility are
207 similar to the one with the bang (``!``) syntax, but with more flexibility and
207 similar to the one with the bang (``!``) syntax, but with more flexibility and
208 power. Magic function start with a percent sign (``%``) or double percent (``%%``).
208 power. Magic function start with a percent sign (``%``) or double percent (``%%``).
209
209
210 A magic call with a sign percent will act only one line:
210 A magic call with a sign percent will act only one line:
211
211
212 .. code-block:: ipython
212 .. code-block:: ipython
213
213
214 In[1]: %xmode
214 In[1]: %xmode
215 Exception reporting mode: Verbose
215 Exception reporting mode: Verbose
216
216
217 And support assignment:
217 And support assignment:
218
218
219 .. code-block:: ipython
219 .. code-block:: ipython
220
220
221 In [1]: results = %timeit -r1 -n1 -o list(range(1000))
221 In [1]: results = %timeit -r1 -n1 -o list(range(1000))
222 1 loops, best of 1: 21.1 µs per loop
222 1 loops, best of 1: 21.1 µs per loop
223
223
224 In [2]: results
224 In [2]: results
225 Out[2]: <TimeitResult : 1 loops, best of 1: 21.1 µs per loop>
225 Out[2]: <TimeitResult : 1 loops, best of 1: 21.1 µs per loop>
226
226
227 Magic with two percent sign can spread over multiple lines, but do not support assignment:
227 Magic with two percent sign can spread over multiple lines, but do not support assignment:
228
228
229 .. code-block:: ipython
229 .. code-block:: ipython
230
230
231 In[1]: %%bash
231 In[1]: %%bash
232 ... : echo "My shell is:" $SHELL
232 ... : echo "My shell is:" $SHELL
233 ... : echo "My disk usage is:"
233 ... : echo "My disk usage is:"
234 ... : df -h
234 ... : df -h
235 My shell is: /usr/local/bin/bash
235 My shell is: /usr/local/bin/bash
236 My disk usage is:
236 My disk usage is:
237 Filesystem Size Used Avail Capacity iused ifree %iused Mounted on
237 Filesystem Size Used Avail Capacity iused ifree %iused Mounted on
238 /dev/disk1 233Gi 216Gi 16Gi 94% 56788108 4190706 93% /
238 /dev/disk1 233Gi 216Gi 16Gi 94% 56788108 4190706 93% /
239 devfs 190Ki 190Ki 0Bi 100% 656 0 100% /dev
239 devfs 190Ki 190Ki 0Bi 100% 656 0 100% /dev
240 map -hosts 0Bi 0Bi 0Bi 100% 0 0 100% /net
240 map -hosts 0Bi 0Bi 0Bi 100% 0 0 100% /net
241 map auto_home 0Bi 0Bi 0Bi 100% 0 0 100% /hom
241 map auto_home 0Bi 0Bi 0Bi 100% 0 0 100% /hom
242
242
243
243
244 Combining it all
244 Combining it all
245 ----------------
245 ----------------
246
246
247 ::
247 ::
248
248
249 find a snippet that combine all that into one thing!
249 find a snippet that combine all that into one thing!
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