在 Python 中以格式(字符串、值)获取列表中每个元组的值平均值

Question

我有一个元组列表，例如：(A, 1), (B, 2), (C, 3), (A, 9), (B, 8).

如何获取引用元组第一个元素的每个值的平均值，而不知道元组的第一个元素的出现次数？

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)]