2019 年 stackoverflow 网站最受欢迎的 20 个 Python 问题

在最新一期的“Python开发者周刊”（Pycoder's weekly）里，我看到一则有意思的分享，故转出来分享给大家。

该分享来自是一份”python weekly reports“，统计了 2019 年里 stackoverflow 网站上支持数最高的 20 个问题。问题列表如下（方括号中的两个数字是其支持数与回答数）：

1. ​​Why does Python's hash of infinity have the digits of π?​​ - [236/3]
2. ​​Is there a more elegant way to express ((x == a and y == b) or (x == b and y == a))?​​ - [105/10]
3. ​​Why can I use a list index as an indexing variable in a for loop?​​ - [92/6]
4. ​​Why does (inf + 0j)*1 evaluate to inf + nanj?​​ - [93/4]
5. ​​Why is f'{{{74}}}' the same as f'{{74}}' with f-Strings?​​ - [88/1]
6. ​​Why does b+=(4,) work and b = b + (4,) doesn't work when b is a list?​​ - [75/7]
7. ​​Why does Python start at index -1 (as opposed to 0) when indexing a list from the end?​​ - [79/7]
8. ​​Why is TensorFlow 2 much slower than TensorFlow 1?​​ - [104/2]
9. ​​Randomness of Python's random​​ - [70/4]
10. ​​Why does Python allow out-of-range slice indexes for sequences?​​ - [72/2]
11. ​​Unexpected behaviour with Python generator​​ - [57/8]
12. ​​What exactly is meant by "partial function" in functional programming?​​ - [55/3]
13. ​​What does a yield inside a yield do?​​ - [56/4]
14. ​​Issues implementing the "Wave Collapse Function" algorithm in Python 2.7​​ - [52/2]
15. ​​Should linear read-shuffled write always be faster than shuffled read-linear write? (Was: Why is fancy assignment slower than fancy lookup?)​​ - [53/5]
16. ​​How to write 2**n - 1 as a recursive function?​​ - [49/7]
17. ​​Why is a for​​ - [53/5]
18. ​​Is there a difference between board[x, y\] and board[x][y]​​ - [47/6]
19. ​​Why was p[:] designed to work differently in these two situations?​​- [51/6]
20. ​​Jupyter notebook: No connection to server because websocket connection fails​​ - [46/4]

不用怀疑，这些内容的支持数和回答数就是那么少。不过也需注意，它统计的是问题本身的支持数，而不是回答的支持数（尽管回答的支持数也很少）。

还有一点需注意，这份报告并非 stackoverflow 网站的官方报告，而且文中也未说明统计口径与筛选标准，所以我们姑且一看。

有些问题可能挺怪的，或者平时不大可能考虑到，比如关于列表的两个问题：为什么从列表末尾查找时是从 -1 开始？为什么列表的切片允许越界？

不少回答都挺有专业精神，往往会带来新的视角和知识信息。比如，关于列表的 -1 索引问题，高票回答中提到了“~”运算符，有这样的用法：

arr = ["a", "b", "c", "d"]
print(arr[~0])   # d
print(arr[~1])   # c

让人眼前一亮！

还有一个问题是：如何优雅地计算 ​​((x == a and y == b) or (x == b and y == a))​​ 这个形式的结果？

高票回答是这样：

初一看，就像看人变戏法一样……

其它问题和回答就不一一说明了，建议感兴趣的同学按图索骥，按部就班，顺藤摸瓜，顺手牵羊……

链接清单：

​​https://python-weekly.blogspot.com/2020/01/20-best-python-questions-at.html?m=1​​

[1] ​​http://stackoverflow.com/questions/56227419​​

[2] ​​http://stackoverflow.com/questions/58435645​​

[3] ​​http://stackoverflow.com/questions/55644201​​

[4] ​​http://stackoverflow.com/questions/58031966​​

[5] ​​http://stackoverflow.com/questions/59359911​​

[6] ​​http://stackoverflow.com/questions/58259682​​

[7] ​​http://stackoverflow.com/questions/55684960​​

[8] ​​http://stackoverflow.com/questions/58441514​​

[9] ​​http://stackoverflow.com/questions/55934019​​

[10] ​​http://stackoverflow.com/questions/54613753​​

[11] ​​http://stackoverflow.com/questions/54245618​​

[12] ​​http://stackoverflow.com/questions/58339040​​

[13] ​​http://stackoverflow.com/questions/55922302​​

[14] ​​http://stackoverflow.com/questions/57049191​​

[15] ​​http://stackoverflow.com/questions/54782033​​

[16] ​​http://stackoverflow.com/questions/58378549​​

[17] ​​http://stackoverflow.com/questions/56288015​​

[18] ​​http://stackoverflow.com/questions/57351363​​

[19] ​​http://stackoverflow.com/questions/56782148​​

[20] ​​http://stackoverflow.com/questions/54963043​​

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