各种推导式

列表推导式：

>>> a = [i for i in range(10) if i % 2 == 0]
>>> a
[0, 2, 4, 6, 8]

字典推导式：

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

集合推导式：

>>> c = {i for i in [1,2,1,1,1,4,3,3,4,4,5]}
>>> c
{1, 2, 3, 4, 5}

没有元组推导式，用元组的规则其实生成的是生成器推导式

>>> d = (i for i in range(10))
>>> d
<generator object <genexpr> at 0x029B6930>
>>> for each in d:
print(each,end=' ')

0 1 2 3 4 5 6 7 8 9