根据计数器值排序列表

Question

如何根据 Counter 对象的值对 python 列表进行排序？

c = Counter({"a": 1, "b": 6, "c":19})
l = ["b", "c", "a"]

# after sorting based on counter values
l = ["c", "b", "a"]

Answer 1

您可以使用 Counter 本身的 most_common 方法而不是 sorted 来获得相同的结果。

most_common = Counter({"a": 1, "b": 6, "c":19}).most_common()

列表理解：

most_common = [item[0] for item in most_common]

操作员：

import operator

most_common = list(map(operator.itemgetter(0), most_common))

结果：

['c', 'b', 'a']

Answer 2

sorted() 采用如下关键函数：

代码：

sorted(l, key=lambda x: -c[x])

或就地为：

l.sort(key=lambda x: -c[x])

测试代码：

from collections import Counter

c = Counter({"a": 1, "b": 6, "c": 19})
l = ["b", "c", "a"]

# after sorting based on counter values
l = ["c", "b", "a"]

print(sorted(l, key=lambda x: -c[x]))

结果：

['c', 'b', 'a']