map,enumerate,zip,filter

#encoding=utf-8


#enumerate 是python中的内置函式
#enumerate(iterable)

 

#适合for循环,可以同时循环序号和元素

mylist=["a","b","c","d","e","f"]
print enumerate(mylist)
for index,object in enumerate(mylist):
print index,object

#结果为
#1 a
#1 b
#2 c
#3 d
#4 e
#5 f

 


#map()
#函式说明map(function,sequence[,sequence,.....])->list
#第一个参数是函数,第二个是列表或元组

print map(lambda x:x*2,[1,2,3,4,5,6,7])

#结果[2, 4, 6, 8, 10, 12, 14]

 

 


#zip
#函式说明 zip(seq1,seq2[.....]) ->[(seq1[0],seq2[0]...),(...)]

print zip([1,2,3,4,5],[11,12,13,14,15],[21,22,23,24,25])

#返回一个列表[(1, 11, 21), (2, 12, 22), (3, 13, 23), (4, 14, 24), (5, 15, 25)]

for x,y in zip([1,2,3],[4,5,6]):
print "x,y:",x,y

 


#filter
#说明: filter(function or None,sequence) ->list,tuple,or string
#参数一:函数 参数二:列表
#根据function参数返回的结果是否为真,来对list进行过滤

print filter(lambda x:x>3,[1,2,3,4,5,6,7])

#结果:[4, 5, 6, 7]