在python中按组获取平均值

Question

输入如下：

G1: 12
G2: 15
G1: 9
G3: 18
G2: 17
G3: 6
G1: 20

输出应为各组的平均值，如G1:12+9+20/3=13.67， G2:15+17/2=16，G3:6+18/2=12

Answer 1

您可以将输入保存到.txt文件，然后可以尝试以下操作：

First method : with collections.defaultdict

import collections
track=collections.defaultdict(list)
with open('file.txt','r') as f:
    for line in f:
        key,value=line.split(':')
        track[key].append(int(value))


print(list(map(lambda x:(x,sum(track[x])/len(track[x])),track.keys())))

输出：

[('G3', 12.0), ('G1', 13.666666666666666), ('G2', 16.0)]

Second method : pure logic without any external module

track={}
with open('file.txt','r') as f:
    for line in f:
        key,value=line.split(':')
        if key not in track:
            track[key]=[int(value)]
        else:
            track[key].append(int(value))

print(list(map(lambda x:(x,sum(track[x])/len(track[x])),track.keys())))

输出：

[('G1', 13.666666666666666), ('G2', 16.0), ('G3', 12.0)]