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Python 的魅力（技巧几则）[编程的日常]

 3 years ago
source link: https://zhuanlan.zhihu.com/p/80261870
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Python 的魅力（技巧几则）[编程的日常]

☑编程 ☑读书 ☑翻译 ☑太极

Python 让我喜欢的一大原因就是解决问题的小手段很多，犹如云中散手，出乎你的意料，让你看了之后恍然大悟：居然如此巧妙，只有想不到，没有做不到。

接下来介绍几个小手段，喜欢就点赞，赞越多今后分享也就越多。๑乛◡乛๑

  • 快速比较列表元素是否相同
from collections import Counter
a = [1, 2, 3]
b = [2, 3, 1]
c = [1, 2]
In [29]: Counter(a) == Counter(b)
Out[29]: True

In [30]: Counter(a) == Counter(c)
Out[30]: False
  • 一种字符串拼接的妙用
In [35]: s =("It is just a very very "
    ...: "long long long long long string.")

In [36]: s
Out[36]: 'It is just a very very long long long long long string.'

In [37]: l = ["abc", "efg" "hij", "klmm"]

In [38]: l
Out[38]: ['abc', 'efghij', 'klmm']

列表里的那个操作尤其骚气了。

  • 有关列表的 print() 操作
In [42]: l = ["abc", "efg", "hij"]

In [43]: print(*l)
abc efg hij

In [44]: print(*l, sep=", ")
abc, efg, hij

In [45]: print(*l, sep=", ", end=".\n")
abc, efg, hij.
  • 自定义“操作符”

大家知道 Python 无法自定义操作符，但是 Python 的小手段 Trick 是层出不穷的。

from functools import partial


class Infix(object):
    def __init__(self, func):
        self.func = func
    def __or__(self, other):
        return self.func(other)
    def __ror__(self, other):
        return Infix(partial(self.func, other))
    def __call__(self, v1, v2):
        return self.func(v1, v2)

然后试试看：

In [48]: @Infix
    ...: def multiply(x, y):
    ...:     return x * y
    ...:

In [49]: 10 |multiply| 9000
Out[49]: 90000

In [50]: curry = Infix(partial)

In [51]: def f(x, y, z):
    ...:     return x + y + z
    ...:

In [52]: g = f |curry| 10 |curry| 20 |curry| 30

In [53]: g()
Out[53]: 60
  • 提取字符串里的容器结构
In [54]: import ast

In [55]: a = "[10, 50, 90]"

In [56]: ast.literal_eval(a)
Out[56]: [10, 50, 90]

In [57]: b = "[10, 50, 90], (60, 130)"

In [58]: ast.literal_eval(b)
Out[58]: ([10, 50, 90], (60, 130))

In [59]: ast.literal_eval(b)[1][1]
Out[59]: 130

好了，我不知道哪种编程语言的 Hack 小手段有 Python 这么多。Python 的开发效率确实高，但不代表 Python 简单。要用好 Python，小手段是很重要的。（＾_＾）


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