看到一篇博文寫lambda和reduce函數，筆者小癢了一下，用Python實現一下：
#! /usr/bin/env python
# -*-coding:utf-8-*-
import time
import math
def test_reduce():
start_time = time.clock()
print reduce[A1] (lambdax,y:x*y[A2] ,range(1,long(input('plz input a num(>0):')+1))[A3] )
print 'Time used:%s' %(time.clock()-start_time)
return;
def test_math():
start_time2 = time.clock()
print math.factorial[A4] (long(raw_input('plz input a num(>0):')))
print 'Time used:%s' %(time.clock()-start_time2)
if __name__ == '__main__':
print '~'*34+'Use reduce'+'~'*34
test_reduce()
print '~'*34+'Use math'+'~'*34
test_math()
Python is Python!
[A1]關於reduce函數的參數及解釋：
reduce(function, iterable[, initializer])
Apply function of two argumentscumulatively to the items of iterable, from left to right, so as to reduce theiterable to a single value. For example, reduce(lambda x, y: x+y, [1, 2, 3, 4,5]) calculates ((((1+2)+3)+4)+5). The left argument, x, is the accumulatedvalue and the right argument, y, is the update value from the iterable. If theoptional initializer is present, it is placed before the items of the iterablein the calculation, and serves as a default when the iterable is empty. Ifinitializer is not given and iterable contains only one item, the first item isreturned.
[A2]關於lambda函數的參數及解釋：
An anonymous inline function consisting ofa single expressionwhich is evaluated when the function is called. The syntax to create a lambdafunction is lambda [arguments]: expression
Lambda expressions (sometimes called lambdaforms) have the same syntactic position as expressions. They are a shorthand tocreate anonymous functions; the expression lambda arguments: expression yieldsa function object. The unnamed object behaves like a function object definedwith
def name(arguments):
return expression
[A4]關於factorial函數的參數及解釋:
math.factorial(x)
Return x factorial. Raises ValueError if x is not integral or is negative.
