列表表达式

sq=[x**x for x in range(10)]

[(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]

[str(round(pi, i)) for i in range(1, 6)]

Basename

In [7]: print(str(os.path.basename("~/das/dsa")))
dsa

循环的技巧

knights = {'gallahad': 'the pure', 'robin': 'the brave'}
for k, v in knights.items():
	print(k, v)
	
for i, v in enumerate(['tic', 'tac', 'toe']):
     print(i, v)

0 tic
1 tac
2 toe

for item in zip([1, 2, 3], ['sugar', 'spice', 'everything nice']):
...     print(item)
...
(1, 'sugar')
(2, 'spice')
(3, 'everything nice')

输入与输出 格式化

## f''
>>> year = 2016
>>> event = 'Referendum'
>>> f'Results of the {year} {event}'
'Results of the 2016 Referendum'

>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%' ## 前面对齐，后面精度

## format
>>> yes_votes = 42_572_654
>>> no_votes = 43_132_495
>>> percentage = yes_votes / (yes_votes + no_votes)
>>> '{:-9} YES votes  {:2.2%}'.format(yes_votes, percentage)
' 42572654 YES votes  49.67%'

迭代器

class Reverse:
    """Iterator for looping over a sequence backwards."""
    def __init__(self, data):
        self.data = data
        self.index = len(data)

    def __iter__(self):
        return self

    def __next__(self):
        if self.index == 0:
            raise StopIteration
        self.index = self.index - 1
        return self.data[self.index]

生成器

>>> g = (x * x for x in range(10))
>>> for n in g:
...     print(n)

>>> L = [x * x for x in range(10)]
>>> L
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
>>> g = (x * x for x in range(10))
>>> g
<generator object <genexpr> at 0x1022ef630>