对整数和字符串的混合列表进行排序 [英] Sorting a mixed list of ints and strings
问题描述
我正在尝试对以下混合的整数和字符串列表进行排序,但是却得到了TypeError.我想要的输出顺序是先对整数排序,再对字符串排序.
I am trying to sort the following mixed list of ints and strings, but getting a TypeError instead. My desired output order is sorted integers then sorted strings.
x=[4,6,9,'ashley','drooks','chay','poo','may']
>>> x.sort()
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
x.sort()
TypeError: '<' not supported between instances of 'str' and 'int'
推荐答案
You can pass a custom key function to list.sort
:
x = [4,6,9,'ashley','drooks','chay','poo','may']
x.sort(key=lambda v: (isinstance(v, str), v))
# result:
# [4, 6, 9, 'ashley', 'chay', 'drooks', 'may', 'poo']
此键函数将列表中的每个元素映射到一个元组,其中第一个值为布尔值(对于字符串,为True
,对于数字为False
),第二个值是元素本身,如下所示:>
This key function maps each element in the list to a tuple in which the first value is a boolean (True
for strings and False
for numbers) and the second value is the element itself, like this:
>>> [(isinstance(v, str), v) for v in x]
[(False, 4), (False, 6), (False, 9), (True, 'ashley'), (True, 'chay'),
(True, 'drooks'), (True, 'may'), (True, 'poo')]
然后使用这些元组对列表进行排序.因为False < True
,这使得整数可以在字符串之前排序.然后,将具有相同布尔值的元素按元组中的第二个值进行排序.
These tuples are then used to sort the list. Because False < True
, this makes it so that integers are sorted before strings. Elements with the same boolean value are then sorted by the 2nd value in the tuple.
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