python之 enumerate()函数

1. 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，一般用来for循环中

例子：

>>>seasons = ['Spring', 'Summer', 'Fall', 'Winter']

>>> list(enumerate(seasons))

[(0, 'Spring'), (1, 'Summer'), (2, 'Fall'), (3, 'Winter')]

---

>>> list(enumerate(seasons, start=1)) # 小标从 1 开始

[(1, 'Spring'), (2, 'Summer'), (3, 'Fall'), (4, 'Winter')]

---

普通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

---

for循环使用enumerate：

>>>seq = ['one', 'two', 'three']

>>> for i, element in enumerate(seq):

...    print i, seq[i]

... 

0 one

1 two

2 three