python中enumerate函数用法实例分析
本文实例讲述了python中enumerate函数用法。分享给大家供大家参考。具体分析如下：
今日发现一个新函数 enumerate 。一般情况下对一个列表或数组既要遍历索引又要遍历元素时，会这样写：
for i in range (0,len(list)): print i ,list[i]
但是这种方法有些累赘，使用内置enumerrate函数会有更加直接，优美的做法，先看看enumerate的定义：
def enumerate(collection): 'Generates an indexed series: (0,coll[0]), (1,coll[1]) ...' i = 0 it = iter(collection) while 1: yield (i, it.next()) i += 1
enumerate会将数组或列表组成一个索引序列。使我们再获取索引和索引内容的时候更加方便如下：
for index，text in enumerate(list)): print index ,text
在cookbook里介绍，如果你要计算文件的行数，可以这样写：
count = len(open(thefilepath,'rU').readlines())
前面这种方法简单，但是可能比较慢，当文件比较大时甚至不能工作，下面这种循环读取的方法更合适些。
Count = -1 For count,line in enumerate(open(thefilepath,'rU'))： Pass Count += 1
希望本文所述对大家的python程序设计有所帮助。
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