Python中zip()函数用法实例教程

> a = [1,2,3]
> b = [4,5,6]
> c = [4,5,6,7,8]
> zipped = zip(a,b)
[(1, 4), (2, 5), (3, 6)]
> zip(a,c)
[(1, 4), (2, 5), (3, 6)]
> zip(*zipped)
[(1, 2, 3), (4, 5, 6)]

a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

print [ [row[col] for row in a] for col in range(len(a[0]))]
[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

> a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
> zip(*a)
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]
> map(list,zip(*a))
[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

> import random
> def random_pick(seq,probabilities):
 x = random.uniform(0, 1)
 cumulative_probability = 0.0
 for item, item_probability in zip(seq, probabilities):
 cumulative_probability += item_probability
 if x < cumulative_probability: break
 return item

> for i in range(15):
 random_pick("abc",[0.1,0.3,0.6])
 
'c'
'b'
'c'
'c'
'a'
'b'
'c'
'c'
'c'
'a'
'b'
'b'
'c'
'a'
'c'