在 Python 中以格式 (string, value) 获取列表中每个元组的值的平均值

Question

我有一个元组列表，例如：(A, 1), (B, 2), (C, 3), (A, 9), (B, 8).如何在不知道元组第一个元素的出现次数的情况下，获取元组第一个元素的每个值的平均值？我想要这样的东西：(A, 5), (B, 5), (C, 3).

Answer 1

使用groupby和itemgetter：

from itertools import groupby

from operator import itemgetter

from statistics import mean

s = [('A', 1), ('B', 2), ('C', 3), ('A', 9), ('B', 8)]

s2 = sorted(s, key=itemgetter(0))   # sorting the tuple based on 0th index

print([(k, int(mean(list(zip(*g))[1]))) for k, g in groupby(s2, itemgetter(0))])

输出：

[('A', 5), ('B', 5), ('C', 3)]

Answer 2

from collections import defaultdict

sample = [("A", 1), ("B", 2), ("C", 3), ("A", 9), ("B", 8)]

store_alphabet_count = defaultdict(list)

for alphabet, count in sample:

    store_alphabet_count[alphabet].append(count)

result = [

    (key, sum(value) // len(value)) for key, value in store_alphabet_count.items()

]

print(result)

输出：

[('A', 5), ('B', 5), ('C', 3)]