如何对字符串列表进行排序?

问题描述

在Python中创建按字母顺序排序的列表的最佳方法是什么?

What is the best way of creating an alphabetically sorted list in Python?

推荐答案

基本答案:

mylist = ["b", "C", "A"]
mylist.sort()

这会修改您的原始列表(即就地排序).要获得列表的排序副本而不更改原始列表，请使用 sorted() 函数:

This modifies your original list (i.e. sorts in-place). To get a sorted copy of the list, without changing the original, use the sorted() function:

for x in sorted(mylist):
    print x

但是，上面的示例有些天真，因为它们没有考虑区域设置，而是执行区分大小写的排序.您可以利用可选参数key来指定自定义排序顺序(使用cmp的替代方法是不建议使用的解决方案，因为必须对其进行多次评估-key每个元素仅计算一次).

However, the examples above are a bit naive, because they don't take locale into account, and perform a case-sensitive sorting. You can take advantage of the optional parameter key to specify custom sorting order (the alternative, using cmp, is a deprecated solution, as it has to be evaluated multiple times - key is only computed once per element).

因此，要根据当前语言环境进行排序，并考虑到特定于语言的规则( cmp_to_key 是functools的帮助函数):

So, to sort according to the current locale, taking language-specific rules into account (cmp_to_key is a helper function from functools):

sorted(mylist, key=cmp_to_key(locale.strcoll))

最后，如果需要，您可以指定自定义语言环境进行排序:

And finally, if you need, you can specify a custom locale for sorting:

import locale
locale.setlocale(locale.LC_ALL, 'en_US.UTF-8') # vary depending on your lang/locale
assert sorted((u'Ab', u'ad', u'aa'),
  key=cmp_to_key(locale.strcoll)) == [u'aa', u'Ab', u'ad']

最后一点:您将看到使用lower()方法的不区分大小写的排序示例-这些是不正确的，因为它们仅适用于ASCII字符集.对于任何非英语数据，这两个都是错误的:

Last note: you will see examples of case-insensitive sorting which use the lower() method - those are incorrect, because they work only for the ASCII subset of characters. Those two are wrong for any non-English data:

# this is incorrect!
mylist.sort(key=lambda x: x.lower())
# alternative notation, a bit faster, but still wrong
mylist.sort(key=str.lower)

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