Python 標準ライブラリ operator 演算

import operator

operator.add(1, 2) # => 3
operator.add("a", "bc") # => 'abc'

operator.abs(-1) # => 1
operator.abs(-2.5) # => 2.5

operator.index(-1) # => -1
# __index__()と同じ
(-1).__index__() # => -1 

operator.countOf([1,2,1,2,3,3,1,2], 1)  # => 3
operator.countOf("aabaabcac", "a")  # => 5

operator.indexOf([1,2,1,2,3,3,1,2], 2)  # => 1
operator.indexOf("aabaabcac", "b")  # => 2

operator.length_hint([1,2,1,2,3,3,1,2])  # => 8
operator.length_hint("aabaabcac")  # => 9

class Name:
    def __init__(self, first, last):
        self.first = first
        self.last = last

class User:
    def __init__(self, first_name, last_name, department):
        self.name = Name(first_name, last_name)
        self.department = department

u = User('Yamada', 'Taro', 'A10')

department_getter = operator.attrgetter('department')
department_name_getter_1 = operator.attrgetter('department', 'name')
department_name_getter_2 = operator.attrgetter('department', 'name.first', 'name.last')

department_getter(u) # => 'A10'
department_name_getter_1(u) # => ('A10', <__main__.Name at 0x2dbc8c2c880>)
department_name_getter_2(u) # => ('A10', 'Yamada', 'Taro')

d = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5}
key_getter_1 = operator.itemgetter('a')
key_getter_2 = operator.itemgetter('c','d')
key_getter_1(d) # => 1
key_getter_2(d) # => (3, 4)

l = [10, 20 ,30, 40, 50]
index_getter_1 = operator.itemgetter(1)
index_getter_2 = operator.itemgetter(3, 4)
index_getter_1(l) # => 20
index_getter_2(l) # => (40, 50)

tuples = [('x',10), ('y',20), ('z',30), ('a',40), ('b', 50)]
tuple_getter = operator.itemgetter(1)
list(map(tuple_getter, tuples)) # => [10, 20, 30, 40, 50]

class SampleClass:
    def sample_method(self,*args, **kwds):
        print(args)
        print(kwds)

sc = SampleClass()
caller = operator.methodcaller('sample_method', 10, 'abc', key1=123, key2='X')
caller(sc) # => (10, 'abc') {'key1': 123, 'key2': 'X'}