Python

Front 1

regular expression replace

Back 1

re.sub(pattern, replace, subject)

Front 2

regular expression search

Back 2

re.search(pattern, subject [, ...])

returns Match object or None

Match.group() - array of matches

Front 3

string replace (not regex)

Back 3

string.replace(search, replacement)

Front 4

find substring

Back 4

string.find(search)

Front 5

iterate through dict

Back 5

for key,value in dict.iteritems()

Front 6

get next item from dictionary

Back 6

dict.iterkeys().next()

dict.iteritems().next()

also: items, keys, values

Front 7

merge dictionaries

Back 7

dict1 = {...}
dict1.update({...})

Front 8

dictionary from two lists

Back 8

newDict = dict(zip(list1, list2))

Front 9

sets - lists with no duplicates

Back 9

set([a, a, b])

-> set([a, b])

Front 10

some obvious list methods, flip a list around?

Back 10

reverse, pop, push, count

Front 11

some coooool list methods

Back 11

list.remove(x), list.index(x), list.count(x)

Front 12

comprehension example

Back 12

fruit = [' banana', ' loganberry ', 'passion fruit ']
fruit2 = [f.strip() for f in fruit]

>>> ['banana', 'loganberry', 'passion fruit']

Front 13

more complex comprehension example

Back 13

pis = [str(round(355/113.0, i)) for i in range(1,6)]

>>>['3.1', '3.14', '3.142', '3.1416', '3.14159']

Front 14

more comprehensions

Back 14

vec = [2, 4, 6]
vec2 = [3*x for x in vec if x > 3]

>>>[12, 18]

vec3 = [[x,x**2] for x in vec]

>>>[[2, 4], [4, 16], [6, 36]]

Front 15

comprehension - iterate through two lists

Back 15

vec1 = [2, 4, 6]
vec2 = [4, 3, -9]

vec3 = [x*y for x in vec1 for y in vec2]

>>>[8, 6, -18, 16, 12, -36, 24, 18, -54]

Front 16

nested comprehension

Back 16

mat = [
... [1, 2, 3],
... [4, 5, 6],
... [7, 8, 9],
... ]

print([[row[i] for row in mat] for i in [0, 1, 2]])

>>>[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

Front 17

iterate through two lists

Back 17

questions = ['name', 'quest', 'favorite color']
answers = ['lancelot', 'the holy grail', 'blue']

for q, a in zip(questions, answers):
... print 'What is your {0}? It is {1}.'.format(q, a)

Front 18

format - more powerful than %

Back 18

'What is your {0}? It is {1}.'.format(q, a)

#allows for reusing args

Front 19

sequence types

Back 19

str, unicode, list, tuple, buffer, xrange

Front 20

unicode string

Back 20

u'abc'

Front 21

return true if any element in the iterable is true

Back 21

any(iterable)

Front 22

convert to binary string

Back 22

bin()

Front 23

convert to bool

Back 23

bool()

Front 24

check if something is callable (class or function...)

Back 24

callable()

Front 25

declare a class method (the same as a static + member method?)

Back 25

class C:
@classmethod
def f(cls, arg1, arg2, ...): ...

Front 26

compare two vars

Back 26

cmp()

Front 27

return the list of Objects (not vars or member values) in the current local scope or in an object

Back 27

dir([object])

Front 28

dir() example

Back 28

>>> import struct
>>> dir() # doctest: +SKIP
['__builtins__', '__doc__', '__name__', 'struct']

Front 29

find the quotient and remainder of two values

Back 29

divmod(a, b)

Front 30

stop!

Back 30

quit(), exit()

Front 31

for overloading comarisons

Back 31

object.__lt__(self, other)
object.__le__(self, other)
object.__eq__(self, other)
object.__ne__(self, other)
object.__gt__(self, other)
object.__ge__(self, other)

Front 32

split

Back 32

re.split('\W+', 'Words, words, words.')

>>>['Words', 'words', 'words', '']

Front 33

regex - return non overlapping matches of a pattern in string

Back 33

re.findall(pattern, string[, flags])

Front 34

regex - return iterator yielding MatchObject fo all non overlapping matches of a pattern in a string

Back 34

re.finditer(pattern, string[, flags])

Front 35

camelize string

Back 35

string.capwords(s[, sep])

Front 36

string - uppercase first letter

Back 36

str.capitalize()

Front 37

string - to lowercase

Back 37

str.lower()

Front 38

str - all to uppercase

Back 38

str.upper()

Front 39

iterate through file system

Back 39

import os

for fileName in os.listdir(directory): pass

Front 40

import a class using a string

Back 40

__import__('filename')

Front 41

make object callable

Back 41

def __call__(self): pass

Front 42

call a local/global function with string

Back 42

globals()["myfunction"]()

locals()["myfunction"]()

Front 43

get len() of an object

Back 43

__len__()

Front 44

try an except

Back 44

try:
pass
except Exception: #or a Exc
pass

Front 45

dict elements

Back 45

dict.values()

dict.keys()

Front 46

call function with arguments list

Back 46

wrapper(*args)

The * next to args means "take the rest of the parameters given and put them in a list called args".

Front 47

call member function

Back 47

getattr(obj, 'str')

Front 48

escape % when formating string

Back 48

"%s%%" % str

Front 49

random numbers within a range

Back 49

print(random.randint(1,10))
//5
print(random.uniform(3.2, 6.7))
//3.4089421725853639

Front 50

time

Back 50

import time
time = time.time()

Front 51

access obj property by string

Back 51

prop = getattr(obj, 'attr')

Front 52

timestamp

Back 52

import time
time - time.time()

Front 53

sort list!

Back 53

newlist = sorted(l, key=lambda k: k['name'])

Front 54

check if file exists

Back 54

os.path.exists("bob.txt")