Python中lambda函数的简单分析（附示例）

def f(x):

return x**2

print f(4)

g = lambda x : x**2

print g(4)

>>> foo = [2, 18, 9, 22, 17, 24, 8, 12, 27]

>>> print filter(lambda x: x % 3 == 0, foo)

[18, 9, 24, 12, 27]

>>> print map(lambda x: x * 2 + 10, foo)

[14, 46, 28, 54, 44, 58, 26, 34, 64]

>>> print reduce(lambda x, y: x + y, foo)

139

from collections import *                                                     

x = defaultdict(lambda:0) //默认值是0

print x[0]

y =defaultdict(lambda:defaultdict(lambda:0))//默认值是一个字典，字典的默认值是0

print y[0]

z = defaultdict(lambda:[0,0,0])//默认值是一个列表，[0,0,0].

print z[0]

0

defaultdict(<function <lambda> at0x7f097797af50>, {})

[0, 0, 0]