marcos-gral Cheat Sheet by Marcos

lambda [parameter_list]: expresion

def func(n):
    """ Documentation """

r = requests.get(url , params={'foo': 'bar'} )
r = requests.post(url , params={'foo': 'bar'} )

r.status_code # 200
r.text
r.json
r.headers
r.encoding # utf-8 / ISO-xxx

import json
url = 'https://api.github.com/some/endpoint'
payload = {'some': 'data'}
headers = {'content-type': 'application/json'}
 
r = requests.post(url, data=json.dumps(payload), headers=headers)

r = requests.put("http://httpbin.org/put")
r = requests.delete("http://httpbin.org/delete")
r = requests.head("http://httpbin.org/get")
r = requests.options("http://httpbin.org/get")

for i in range(start,stop,step):
    stuff

for value in [sequence]:
    stuff

for position, value in enumerate(sequence):
    stuff

for a,b in zip(first, second):
   stuff

for ###
else
    stuff to do at end of loop (usually exception when breaking in loop)

while condition:
    stuff
else
    stuff to do when condition is false

break # breaks the loop
continue # continue at the start of the loop body

"­Hello, {0} {1}".fo­rma­t("a­be", "­jon­es")
Hello, abe jones

"­Hello, {fn} {ln}".f­orm­at(­fn=­"­abe­", ln="­jon­es")
Hello, abe jones

"You owe me ${0:,.2­f}­".fo­rma­t(2­534­22.3)
You owe me $253,4­22.30

now = dateti­me.n­ow()
'{:%Y-­%m-%d %H:%M:­%S}­'.f­orm­at(now)
2012-­05-16 15:04:33

try:
except ExceptionName as e:
except (ExceptionName, OtherException) as e:
else:
    # do something when no exception
finally:
    # do something anyway, exception or not

Loop Over Sequence
for index, value in enumer­ate­(seq):
 ­ ­pri­nt(­"{} : {}".f­or­mat­(index, value))

Loop Over Dictio­nary
for key in sorted­(dict):
 ­ ­pri­nt(­dic­t[key])

Read a File
with open("f­ile­nam­e", "­r") as f:
 ­ for line in f:
 ­ ­ ­ line = line.r­str­ip(­"­\n") # Strip newline
 ­ ­ ­ ­pri­nt(­line)

def wrap(func):
    def wrapper(args, *kwargs):
        # do something about func
        func(args, *kwargs)
        # do something about func
    return wrapper

# Apply decorator
def to_decorate(...):
# body	
to_decorate = wrap(to_decorate)	

# More idiomatic
@wrap
def to_decorate(...):
#body


from functools import wraps
@wraps(func)
def wrapper(...) # to keep the name and doc from the wrapped function

# Decorator with args: make a decorator factory
def decorator_factory(factory_args):
    def decorator(func):
        def wrapper(args, *kwargs):
            # do something about func
            func(args, *kwargs)
            # do something about func
        return wrapper
    return decorator


@decorator_factory(1,2...)
def to_decorate(...):

class zrange_iter:
    def __init__(self, n):
        self.i = 0
        self.n = n

    def __iter__(self):
        # Iterators are iterables too.
        # Adding this functions to make them so.
        return self

    def next(self):
        if self.i < self.n:
            i = self.i
            self.i += 1
            return i
        else:
            raise StopIteration()

def firstn(n):
    num = 0
    while num < n:
        yield num
        num += 1

sum_of_first_n = sum(firstn(1000000))

# yield from my_gen(x)

g = my_gen(x)
try:
    next(g)
except StopIteration:
    pass

# Unpacking Generators

>>> g1 = (x for x in range(3))
>>> g2 = (x**2 for x in range(2))
>>> [1, g1, 2, g2]
[1, 0, 1, 2, 2, 0, 1]

>>> g = (x for x in range(3))
>>> a, b, c = g
>>> print(a, b, c)
0 1 2
>>> g = (x for x in range(6))
>>> a, b, *c, d = g
>>> print(a, b, d)
0 1 5
>>> print(c)
[2, 3, 4]