Python中的枚举（）

通常，在处理迭代器时，我们还需要保持迭代计数。 Python通过为该任务提供内置函数enumerate() 来简化程序员的任务。
Enumerate() 方法向可迭代对象添加一个计数器，并以枚举对象的形式返回它。然后这个枚举对象可以直接用于循环或使用 list() 方法转换为元组列表。

句法：

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

Python3

# python
# 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)))

输出：

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

在循环中使用枚举对象：

Python3

# 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)
  
# changing index and printing separately
for count, ele in enumerate(l1, 100):
    print (count, ele)
  
# getting desired output from tuple
for count, ele in enumerate(l1):
    print(count)
    print(ele)

输出：

(0, 'eat')
(1, 'sleep')
(2, 'repeat')
100 eat
101 sleep
102 repeat
0
eat
1
sleep
2
repeat