Backport PR #10760: Small fix: Bang should be after the assignment operator

docs/source/interactive/python-ipython-diff.rst

@@ -1,249 +1,249
 =================
 Python vs IPython
 =================
 
 This document is meant to highlight the main differences between the Python
 language and what are the specific construct you can do only in IPython.
 
 Unless expressed otherwise all of the construct you will see here will raise a
 ``SyntaxError`` if run in a pure Python shell, or if executing in a Python
 script.
 
 Each of these features are describe more in details in further part of the documentation.
 
 
 Quick overview:
 ===============
 
 
 All the following construct are valid IPython syntax:
 
 .. code-block:: ipython
 
     In [1]: ?
 
 .. code-block:: ipython
 
     In [1]: ?object
 
 
 .. code-block:: ipython
 
     In [1]: object?
 
 .. code-block:: ipython
 
     In [1]: *pattern*?
 
 .. code-block:: ipython
 
     In [1]: %shell like --syntax
 
 .. code-block:: ipython
 
     In [1]: !ls
 
 .. code-block:: ipython
 
     In [1]: my_files =! ls ~/
     In [1]: for i,file in enumerate(my_file):
        ...:     raw = !echo $file
        ...:     !echo {files[0].upper()} $raw
 
 
 .. code-block:: ipython
 
     In [1]: %%perl magic --function
        ...: @months = ("July", "August", "September");
        ...: print $months[0];
 
 
 Each of these construct is compile by IPython into valid python code and will
 do most of the time what you expect it will do. Let see each of these example
 in more detail.
 
 
 Accessing help
 ==============
 
 As IPython is mostly an interactive shell, the question mark is a simple
 shortcut to get help. A question mark alone will bring up the IPython help:
 
 .. code-block:: ipython
 
     In [1]: ?
 
     IPython -- An enhanced Interactive Python
     =========================================
 
     IPython offers a combination of convenient shell features, special commands
     and a history mechanism for both input (command history) and output (results
     caching, similar to Mathematica). It is intended to be a fully compatible
     replacement for the standard Python interpreter, while offering vastly
     improved functionality and flexibility.
 
     At your system command line, type 'ipython -h' to see the command line
     options available. This document only describes interactive features.
 
     MAIN FEATURES
     -------------
     ...
 
 A single question mark before, or after an object available in current
 namespace will show help relative to this object:
 
 .. code-block:: ipython
 
     In [6]: object?
     Docstring: The most base type
     Type:      type
 
 
 A double question mark will try to pull out more information about the object,
 and if possible display the python source code of this object.
 
 .. code-block:: ipython
 
     In[1]: import collections
     In[2]: collection.Counter??
 
     Init signature: collections.Counter(*args, **kwds)
     Source:
     class Counter(dict):
         '''Dict subclass for counting hashable items.  Sometimes called a bag
         or multiset.  Elements are stored as dictionary keys and their counts
         are stored as dictionary values.
 
         >>> c = Counter('abcdeabcdabcaba')  # count elements from a string
 
         >>> c.most_common(3)                # three most common elements
         [('a', 5), ('b', 4), ('c', 3)]
         >>> sorted(c)                       # list all unique elements
         ['a', 'b', 'c', 'd', 'e']
         >>> ''.join(sorted(c.elements()))   # list elements with repetitions
         'aaaaabbbbcccdde'
         ...
 
 
 
 If you are looking for an object, the use of wildcards ``*`` in conjunction
 with question mark will allow you to search current namespace for object with
 matching names:
 
 .. code-block:: ipython
 
     In [24]: *int*?
     FloatingPointError
     int
     print
 
 
 Shell Assignment
 ================
 
 
 When doing interactive computing it is common to need to access the underlying shell.
 This is doable through the use of the exclamation mark ``!`` (or bang).
 
 This allow to execute simple command when present in beginning of line:
 
 .. code-block:: ipython
 
     In[1]: !pwd
     /User/home/
 
 Change directory:
 
 .. code-block:: ipython
 
     In[1]: !cd /var/etc
 
 Or edit file:
 
 .. code-block:: ipython
 
     In[1]: !mvim myfile.txt
 
 
 The line after the bang can call any program installed in the underlying
 shell, and support variable expansion in the form of ``$variable`` or ``{variable}``.
 The later form of expansion supports arbitrary python expression:
 
 .. code-block:: ipython
 
     In[1]: file = 'myfile.txt'
 
     In[2]: !mv $file {file.upper()}
 
 
 The bang can also be present in the right hand side of an assignment, just
 after the equal sign, or separated from it by a white space. In which case the
 standard output of the command after the bang ``!`` will be split out into lines
 in a list-like object and assign to the left hand side.
 
 This allow you for example to put the list of files of the current working directory in a variable:
 
 .. code-block:: ipython
 
-    In[1]: my_files != ls
+    In[1]: my_files = !ls
 
 
 You can combine the different possibilities in for loops, condition, functions...:
 
 .. code-block:: ipython
 
     my_files =! ls ~/
     b = "backup file"
     for i,file in enumerate(my_file):
         raw = !echo $backup $file
         !cp $file {file.split('.')[0]+'.bak'}
 
 
 Magics
 ------
 
 Magics function are often present in the form of shell-like syntax, but are
 under the hood python function. The syntax and assignment possibility are
 similar to the one with the bang (``!``) syntax, but with more flexibility and
 power. Magic function start with a percent sign (``%``) or double percent (``%%``).
 
 A magic call with a sign percent will act only one line:
 
 .. code-block:: ipython
 
     In[1]: %xmode
     Exception reporting mode: Verbose
 
 And support assignment:
 
 .. code-block:: ipython
 
     In [1]: results = %timeit -r1 -n1 -o list(range(1000))
     1 loops, best of 1: 21.1 µs per loop
 
     In [2]: results
     Out[2]: <TimeitResult : 1 loops, best of 1: 21.1 µs per loop>
 
 Magic with two percent sign can spread over multiple lines, but do not support assignment:
 
 .. code-block:: ipython
 
     In[1]: %%bash
     ...  : echo "My shell is:" $SHELL
     ...  : echo "My disk usage is:"
     ...  : df -h
     My shell is: /usr/local/bin/bash
     My disk usage is:
     Filesystem      Size   Used  Avail Capacity  iused   ifree %iused  Mounted on
     /dev/disk1     233Gi  216Gi   16Gi    94% 56788108 4190706   93%   /
     devfs          190Ki  190Ki    0Bi   100%      656       0  100%   /dev
     map -hosts       0Bi    0Bi    0Bi   100%        0       0  100%   /net
     map auto_home    0Bi    0Bi    0Bi   100%        0       0  100%   /hom
 
 
 Combining it all
 ----------------
 
 ::
 
     find a snippet that combine all that into one thing!