it-ebooks - Tiny Python & ES6 Notebook

From: mattharrison/Tiny-Python-2.7-Notebook

From: mattharrison/Tiny-Python-3.6-Notebook

From: mattharrison/Tiny-es6-Notebook

To check if Python is installed, run the following from a terminal:

python --version

Otherwise, install Python from the website .

http://python.org

The Python executable will behave differently depending on the command line options you give it:

• Start the Python REPL:

  python

• Execute the file.py file:

  python file.py

• Execute the file.py file, and drop into REPL with namespace of file.py:

  python -i file.py

• Execute the json/tool.py module:

  python -m json.tool

• Execute "print 'hi'"

  python -c "print 'hi'"

• Use the help function to read the documentation for a module/class/function. As a standalone invocation,you enter the help system and can explore various topics.
• Use the dir function to list contents of the namespace, or attributes of an object if you pass one in

Note

The majority of code in this book is written as if it where executed in a REPL. If youare typing it in, ignore the primary and secondary prompts (>>> and ...).

This is not so much an instructional manual, but rather notes, tables, andexamples for Python syntax. It was created by the author as an additionalresource during training, meant to be distributed as a physical notebook.Participants (who favor the physical characteristics of dead tree material)could add their own notes, thoughts, and have a valuable referenceof curated examples.

Run the following in an interpreter to get an easter egg that describes some of the ethos behind Python. This is also codified in PEP 20:

>>> import thisThe Zen of Python, by Tim PetersBeautiful is better than ugly.Explicit is better than implicit.Simple is better than complex.Complex is better than complicated.Flat is better than nested.Sparse is better than dense.Readability counts.Special cases aren't special enough to break therules.Although practicality beats purity.Errors should never pass silently.Unless explicitly silenced.In the face of ambiguity, refuse the temptationto guess.There should be one --and preferably only one--obvious way to do it.Although that way may not be obvious at firstunless you're Dutch.Now is better than never.Although never is often better than *right* now.If the implementation is hard to explain, it's abad idea.If the implementation is easy to explain, it maybe a good idea.Namespaces are one honking great idea -- let'sdo more of those!

These might just seem like silly one liners, but there is a lot of wisdompacked in here. It is good for Python programmers to review theseevery once in a while and see if these hold true for their code. (Or tojustify their code reviews)

In the default namespace you have access to various callables:

Built in callables

Operation	Result
abs(x)	Absolute value protocol (call x.__abs__())
all(seq)	Boolean check if all items in seq are truthy
any(seq)	Boolean check if at least one item in seq is truthy
apply(callable, [args, [kwargs])	Call callable(*args, **kwargs)
bin(i)	String containing binary version of number (int(bin(i), 2) to reverse)
bool(x)	Boolean protocol (call x.__nonzero__() then x.__len__())
buffer(obj, [offset, [size])	Create buffer object from obj
bytearray(x)	Create a mutable bytearray from iterable of ints, text string, bytes, an integer, or pass nothing for an empty bytearray
bytes(x)	Create an immutable bytes from iterable of ints, text string, bytes, an integer, or pass nothing for an empty bytes
callable(x)	Boolean check if you can do x() (ie x.__call__ exists)
chr(i)	Convert integer codepoint to Unicode string (ord(chr(i)) to reverse)
@classmethod	Use to decorate a method so you can invoke it on the class
cmp(a, b)	-1, 0, or 1 if a <, == or > b
coerce(num1, num2)	Coerce nums to common type
compile(source, fname, mode)	Compile source to code (fname used for error, mode is exec: module, single: statement, eval: expression). Can run eval(code) on expression, exec(code) on statement
complex(i, y)	Create complex number
copyright	Python copyright string
credits	Python credits string
delattr(obj, attr)	Remove attribute from obj (del obj.attr)
dict([x])	Create a dictionary from a mapping, iterable of k,v tuples, named parameters, or pass nothing for an empty dictionary
dir([obj])	List attributes of obj, or names in current namespace if no obj provided
divmod(num, denom)	Return tuple pair of num//denom and num%denom
enumerate(seq, [start])	Return iterator of index, item tuple pairs. Index begins at start or 0 (default)
eval(source, globals=None, locals=None)	Run source (expression string or result of compile) with globals and locals
execfile(filename, globals=None, locals=None)	Run code in filename with globals and locals
exit(code)	Exit Python interpreter and return code
file(name, [mode, [buffering]])	Open a file with mode
filter([function], seq)	Return iterator of items where function(item) is truthy (or item is truthy if function is missing)
float(x)	Convert string or number to float (call x.__float__())
format(obj, fmt)	Format protocol (call obj.__format__(fmt))
frozenset([seq])	Create frozenset from seq (empty if missing)
getattr(obj, attr)	Get attribute from obj (obj.attr)
globals()	Return mutable dictionary with current global variables
hasattr(obj, attr)	Check if attribute on obj (obj.attr doesn't throw AttributeError)
hash(x)