python lambda函数

lambda：匿名函数
lambda函数是一种快速定义单行的最小函数，从Lisp借用而来，可以用在任何函数的地方。

lambd语句中，冒号前是参数，可以有多个以逗号分开的参数；冒号后面是返回值。lambda语句构建的其实是一个函数对象.

>>> g = lambda x,y:x+y>>> g<function <lambda> at 0x23556e0>

reduce为逐次操作list里的每一项，接收的参数为两个，最后返回一个结果。

>>> def add0(x,y)>>>     return x+y>>> sum=reduce(add0,(1,2,3))>>> 6

user1@ubuntu:~$ pythonPython 2.7.3 (default, Sep 26 2013, 20:03:06) [GCC 4.6.3] on linux2Type "help", "copyright", "credits" or "license" for more information.>>> def f(x,y):...     return x*y... >>> f(2,3)6>>> g = lambda x,y:x*y>>> g(2,3)6>>> lambda x,y:x*y<function <lambda> at 0x2355668>>>> g = lambda x,y:x+y>>> g<function <lambda> at 0x23556e0>>>> g(6,2)8>>> 5*4*3*2*1120>>>user1@ubuntu:~$ pythonPython 2.7.3 (default, Sep 26 2013, 20:03:06) [GCC 4.6.3] on linux2Type "help", "copyright", "credits" or "license" for more information.>>> l = range(1,6)>>> l[1, 2, 3, 4, 5]>>> def f(x,y):...     return x*y... >>> reduce(f,l)120>>> f = lambda x,y:x*y>>> reduce(f,l)120>>> >>> >>> reduce(lambda x,y:x*y ,l)120>>> sum = reduce(lambda x,y:x+y,(1,2,3))>>> sum6>>>