Python enumerate()

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。

Python 2.3. 以上版本可用，2.6 添加 start 参数。

Syntax:

enumerate(iterable, start=0)

Parameters:
Iterable: any object that supports iteration
Start: the index value from which the counter is 
              to be started, by default it is 0

参数

iterable -- 一个序列、迭代器或其他支持迭代对象。
start -- 下标起始位置。

# Python program to illustrate 
# enumerate function 
l1 = ["eat","sleep","repeat"] 
s1 = "geek"
  
# creating enumerate objects 
obj1 = enumerate(l1) 
obj2 = enumerate(s1) 
  
print "Return type:",type(obj1) 
print list(enumerate(l1)) 
  
# changing start index to 2 from 0 
print list(enumerate(s1,2)) 

Output:

Return type: < type 'enumerate' >
[(0, 'eat'), (1, 'sleep'), (2, 'repeat')]
[(2, 'g'), (3, 'e'), (4, 'e'), (5, 'k')]

# Python program to illustrate 
# enumerate function in loops 
l1 = ["eat","sleep","repeat"] 
  
# printing the tuples in object directly 
for ele in enumerate(l1): 
    print ele 
print 
# changing index and printing separately 
for count,ele in enumerate(l1,100): 
    print count,ele 

Output:

(0, 'eat')
(1, 'sleep')
(2, 'repeat')

100 eat
101 sleep
102 repeat