# 枚举 Enumerate

枚举（`enumerate`）是 Python 内置函数。它的用处很难在简单的一行中说明，但是大多数的新人，甚至一些高级程序员都没有意识到它。

它允许我们遍历数据并自动计数，

下面是一个例子：

```python
for counter, value in enumerate(some_list):
    print(counter, value)
```

不只如此，`enumerate` 也接受一些可选参数，这使它更有用。

```python
my_list = ['apple', 'banana', 'grapes', 'pear']
for c, value in enumerate(my_list, 1):
    print(c, value)

# 输出:
(1, 'apple')
(2, 'banana')
(3, 'grapes')
(4, 'pear')
```

上面这个可选参数允许我们定制从哪个数字开始枚举。\
你还可以用来创建包含索引的元组列表， 例如：

```python
my_list = ['apple', 'banana', 'grapes', 'pear']
counter_list = list(enumerate(my_list, 1))
print(counter_list)
# 输出: [(1, 'apple'), (2, 'banana'), (3, 'grapes'), (4, 'pear')]
```


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