学习python(四)

学习http://www.cnblogs.com/vamei/archive/2012/07/09/2582435.html

1. 利用range(), 得到下标

S = 'abcdefghijk'for i in range(0,len(S),2):    print S[i]

2. 利用enumerate(), 同时得到下标和元素

S = 'abcdefghijk'for (index,char) in enumerate(S):    print index    print char

3. 利用zip(), 实现并行循环

ta = [1,2,3]tb = [9,8,7]
# clusterzipped = zip(ta,tb)print(zipped)

# decompose
na, nb = zip(*zipped)
print(na, nb)

4.生成器

def gen():    a = 100    yield a    a = a*8    yield a    yield 1000

for i in gen():    print i

yield

def gen():    for i in range(4):        yield i

==

G = (x for x in range(4))

L = []for x in range(10):    L.append(x**2)
==

L = [x**2 for x in range(10)]
xl = [1,3,5]yl = [9,12,13]L  = [ x**2 for (x,y) in zip(xl,yl) if y > 10] [9,25]