碰到的"函数"记录

1.内建函数---enumerate():枚举:

enumerate(sequence, [start=0])

enumerate() 函数用于将一个可遍历的数据对象(如列表、元组或字符串)组合为一个索引序列，同时列出数据和数据下标，一般用在 for 循环当中:

>>>seasons = ['Spring', 'Summer', 'Fall', 'Winter']
>>> list(enumerate(seasons))
[(0, 'Spring'), (1, 'Summer'), (2, 'Fall'), (3, 'Winter')]
>>> list(enumerate(seasons, start=1))       # 下标从 1 开始
[(1, 'Spring'), (2, 'Summer'), (3, 'Fall'), (4, 'Winter')]
# 普通的for循环
>>>i = 0
>>> seq = ['one', 'two', 'three']
>>> for element in seq:
...     print i, seq[i]
...     i +=1
... 
0 one
1 two
2 three
# 使用enumerate
>>>seq = ['one', 'two', 'three']
>>> for i, element in enumerate(seq):
...     print i, element
... 
0 one
1 two
2 three