Python: Useful functions

Abstract: Skills of python useful functions

1. The function get()

>>> print d

{0: '1', 1: 'a12', 2: 'b34'}

>>> for i in range(10):

... d[i]=d.get(i*10, 0) #the default value when no the key

>>> print d

{0: '1', 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0, 8: 0, 9: 0}

2. The function Counter() from collections

>>> from collections import Counter

>>> Counter("Good morning")

Counter({'o': 3, 'n': 2, ' ': 1, 'd': 1, 'G': 1, 'i': 1, 'm': 1, 'g': 1, 'r': 1})

3. The function combinations() from itertools

>>> a=[1,2,3,4]

>>> from itertools import combinations

>>> c=[cc for cc in combinations(a,2)]

>>> print c

[(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]

4. Get all defaults objects

>>> a

[1, 2, 3, 4]

>>> dir(a)

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__delslice__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getslice__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__setslice__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

writing date: 20150522