python - 在 Python 中读取 csv 文件并创建字典

Question

我有一个这样的 csv 数据集:

A, 10, USA
B,30, UK
C,4,IT
A,20,UK
B,10,USA

我想读取此 csv 行并提供以下输出:

A has ran 30 miles with average of 15. 
B has ran 30 miles with average of 20.
C has ran 4 miles with average of 4. 

到目前为止，我的解决方案是读取 csv 数据并将它们转换为字典，然后遍历它们以查看“A”重复了多少次以及它必须计算哪些值来计算平均值并最终生成结果.我已经编写了这段代码，但我很难有效地计算 A 重复的次数并将英里数相加以创建我的最终输出。在 Python 中做这个有什么想法吗？在 C# 中执行此操作对我来说有点容易，但我不太擅长 Python。

def main(filename):
    f = open(filename,'r')
    labels = ['name','miles','country']
    data = csv.DictReader(f,labels,delimiter=',')
    for line in data:
        print (line['name']+"  " + "has ran" +"   "+  line['miles']+" "+"miles")

    f.close()

Answer 1

您可以使用defaultdict 来存储值，然后将它们打印出来:

import csv

from collections import defaultdict

with open(filename, 'r') as handle:
    reader = csv.DictReader(handle, ['name', 'miles', 'country'])
    data = defaultdict(list)

    for line in reader:
        data[line['name']).append(int(line['miles']))

    for runner, distances in data.items():
        print '{} ran a total of {} miles and an average of {} miles'.format(
            runner, sum(distances), sum(distances) / float(len(distances))
        )