【测试开发】python系列教程：Python 推导式

[表达式 for 变量 in 列表]

>>> listone=['a','b']
>>> [item.upper() for item in listone]
['A', 'B']

>>> [i  for i in range(100) if i %2==0]
[0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 
28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 
52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 
78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98]

>>> listone2=['ad','nd']
>>> [word.title() if word.startswith('p')
     else word.upper() for word in listone2]
['AD', 'ND']

{ key_expr: value_expr for value in collection }

>>> dictone={i: i%2==0 for i in range(10)}
>>> dictone
{0: True, 1: False, 2: True, 3: False, 4: True, 5: False,
 6: True, 7: False, 8: True, 9: False}
 

{ expression for item in Sequence }

>>> setd={i**2 for i in range(5)}
>>> setd
{0, 1, 4, 9, 16}

(expression for item in Sequence )

>>> a=(x for x in range(5))
>>> a
<generator object <genexpr> at 0x7fab7a6a3040> #a的迭代
>>> tuple(a)
(0, 1, 2, 3, 4)