Up To Schedule - Return To Write Code for People
Based on Lecture Materials By: Milad Fatenejad, Katy Huff, Tommy Guy, Joshua R. Smith, Will Trimble, and many more
You can run python commands in a handful of ways; you can create executable scripts, you can run the python interpreter, you can run iPython, or you can run iPython notebook. iPython is an alternative to the built-in Python interpreter with some nice features. iPython notebook gives you interactive access to the python interpreter from within a browser window, and it allows you to save your commands as a "notebook".
Lets give the built-in interpreter a spin just this once:
frodgers@acibootcamp ~ $ python
Enthought Python Distribution -- www.enthought.com
Version: 7.3-2 (64-bit)
Python 2.7.3 |EPD 7.3-2 (64-bit)| (default, Apr 11 2012, 17:52:16)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "credits", "demo" or "enthought" for more information.
>>> print "Hello World"
Hello World
>>> quit()
We can also write python commands in a file and execute them from the command line. You will notice that the print command above is located in the file hello.py. Execute the following command at the command line:
frodgers@acibootcamp ~ $ python ~/boot-camps/python/ipython/hello.py
hello world
iPython has more useful features for interactive use than the standard python interpreter, so we'll use it from here on out:
frodgers@acibootcamp ~ $ ipython
Enthought Python Distribution -- www.enthought.com
Python 2.7.3 |EPD 7.3-2 (64-bit)| (default, Apr 11 2012, 17:52:16)
Type "copyright", "credits" or "license" for more information.
IPython 0.12.1 -- An enhanced Interactive Python.
? -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help -> Python's own help system.
object? -> Details about 'object', use 'object??' for extra details.
In [1]: print "Hello World"
Hello World
In [2]:
Unfortunately pasting depends on your operating system and ssh program. In
general, for multi-line pasting, you should use the %cpaste feature of iPython.
When in the iPython interpreter, the easiest way to paste is with the right mouse button over the window, choosing "Paste".
Click with the right mouse button over the window.
#### Mac OSX Press ⌘+V.
Click with the right mouse button over the window and then "Paste".
iPython has a history. If you press the up and down keys, you can access the history. Try it now.
iPython also has tab completion of previous commands. Try typing "pr" and then hit the tab key. What if you type "pri" followed by tab?
iPython has some nice help features.
If you wanted to see all the built-in commands available for something, use
the dir command.
In [2]: dir(__builtin__)
['ArithmeticError',
'AssertionError',
'AttributeError',
'BaseException',
'BufferError',
'BytesWarning',
'DeprecationWarning',
'EOFError',
'Ellipsis',
'EnvironmentError',
'Exception',
'False',
'FloatingPointError',
....
'round',
'set',
'setattr',
'slice',
'sorted',
'staticmethod',
'str',
'sum',
'super',
'tuple',
'type',
'unichr',
'unicode',
'vars',
'xrange',
'zip']
str is the python name for strings.
Let's say we want to know what you can do with strings in python. We can type dir(str)
In [6]: dir(str)
['__add__',
'__class__',
'__contains__',
'__delattr__',
'__doc__',
'__eq__',
'__format__',
'__ge__',
'__getattribute__',
'__getitem__',
'__getnewargs__',
'__getslice__',
'__gt__',
'__hash__',
'__init__',
'__le__',
'__len__',
'__lt__',
'__mod__',
...
'replace',
'rfind',
'rindex',
'rjust',
'rpartition',
'rsplit',
'rstrip',
'split',
'splitlines',
'startswith',
'strip',
'swapcase',
'title',
'translate',
'upper',
'zfill']
Let's look up what some of these functions do.
? displays more information about each datatype/ function. Let's try str.swapcase?.
In [7]: str.swapcase?
Type: method_descriptor
String Form:<method 'swapcase' of 'str' objects>
Namespace: Python builtin
Docstring:
S.swapcase() -> string
Return a copy of the string S with uppercase characters converted to lowercase and vice versa.
In [8]: "Hello world".swapcase()
Out[8]: 'hELLO WORLD'
Exercise
Can you find with help of the ? which function turns "Hello world" into "HELLO WORLD"?
If your code is in a file, you can execute it from the iPython shell with the %run command. Execute hello.py like so:
In [9] %run ~/boot-camps/python/ipython/hello.py
To clear everything from iPython, use the reset command.
In [10] reset
Once deleted, variables cannot be recovered. Proceed (y/[n])?
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