列表推导式

常用写法

1. 单层循环

            ```python
   

   [x * x for x in range(1, 11)] [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

            ```
   

            ```python
   

   d = {'x': 'A', 'y': 'B', 'z': 'C' } [k + '=' + v for k, v in d.iteritems()] ['y=B', 'x=A', 'z=C']

            ```
   

2. 双层循环

            ```python
   

   [m + n for m in 'ABC' for n in 'XYZ'] ['AX', 'AY', 'AZ', 'BX', 'BY', 'BZ', 'CX', 'CY', 'CZ']

            ```
   

3. 循环 + 条件判断

            ```python
   

   [x * x for x in range(1, 11) if x % 2 == 0] [4, 16, 36, 64, 100]

            ```
   

一些写法上的格式

Harmful

comment_ids = (featured_comment_ids + [i.id for i in all_comments.result if i.id not in featured_comment_ids])

Idiomatic

comment_ids = [comment_id 
                for comment_id in comment_ids
                if comment_id not in collapsed_comment_ids]

例如：

• 使用列表推导式、字典推导式等来提高编码效率：