Python字典语法求助：CSV选举数据的候选人票数存储与展示

第一次用Python字典处理CSV格式的选举数据，想把候选人姓名和对应票数存入字典，最终输出如下格式的结果：

Election Results
-------------------------
Total Votes: 369711
-------------------------
Charles Casper Stockham: 23.049% (85213)
Diana DeGette: 73.812% (272892)
Raymon Anthony Doane: 3.139% (11606)

目前已经能统计出各候选人的票数，但字典用法不对，原代码如下：

# Import the os module
import os

# Module for reading CSV files
import csv

# Store the file path associated with the file
csvpath = os.path.join('Resources', 'election_data.csv')

# Open the file "read mode" and store contents in the variable
with open(csvpath) as csvfile:

    csvreader = csv.reader(csvfile, delimiter =',')

    print(csvreader)

    csv_header = next(csvreader)

    total_ballots = 0 
    sumCharles = sumDiana = sumRaymon = 0
    candidates = dict()
    candidates_list = ["Charles Casper Stockham","Diana DeGette","Raymon Anthony Doane"]
    candidates["names"] = candidates_list
    votes_list = [sumCharles , sumDiana , sumRaymon]
    candidates["votes"] = votes_list

    for row in csvreader:
        total_ballots = total_ballots + 1
        if (row[2] == "Charles Casper Stockham"):
            sumCharles = sumCharles + 1
        if (row[2] == "Diana DeGette"):
            sumDiana = sumDiana + 1
        if (row[2] == "Raymon Anthony Doane"):
            sumRaymon = sumRaymon + 1
    
    print(candidates)
    print(total_ballots)

你现在的字典结构把姓名和票数拆成两个列表，后续处理很麻烦。正确的做法是用候选人姓名作为字典的键，票数作为对应的值，操作起来直接高效。优化后的代码如下：

import os
import csv

csvpath = os.path.join('Resources', 'election_data.csv')

with open(csvpath) as csvfile:
    csvreader = csv.reader(csvfile, delimiter=',')
    next(csvreader)  # 跳过表头
    
    total_ballots = 0
    candidate_votes = {}  # 键：候选人姓名，值：票数

    for row in csvreader:
        total_ballots += 1
        candidate = row[2]
        # 如果候选人已在字典中，票数+1；否则初始化票数为1
        if candidate in candidate_votes:
            candidate_votes[candidate] += 1
        else:
            candidate_votes[candidate] = 1

    # 输出结果
    print("Election Results")
    print("-------------------------")
    print(f"Total Votes: {total_ballots}")
    print("-------------------------")
    # 遍历字典计算百分比并输出
    for name, votes in candidate_votes.items():
        percentage = (votes / total_ballots) * 100
        # 格式化百分比为三位小数
        print(f"{name}: {percentage:.3f}% ({votes})")

关键改进点： #

1. 字典结构优化：直接用{候选人: 票数}的键值对存储，无需单独维护姓名列表和票数列表，逻辑更清晰
2. 兼容性更强：就算CSV里出现新的候选人，代码也能自动统计，不用提前手动添加候选人名称
3. 输出逻辑简化：遍历字典的键值对就能直接计算百分比并按要求格式输出，不用再对应索引找数据

内容的提问来源于stack exchange，提问作者Itsnhantransitive