如何统计CSV数据中的团队总数？修复TypeError: object of type 'int' has no len()错误

我正在尝试统计数据里的团队总数，写了如下Python代码：

import pandas as pd
df = pd.read_csv('https://raw.githubusercontent.com/avinashjairam/avinashjairam.github.io/master/question2_data%20.csv', header=None)
for index, rows in df.iterrows():
    team_info = rows.to_list()
    team_id = team_info[0]
    wins = team_info[1]
    losses = team_info[2]
    ties = team_info[3]
    print(team_id, wins, losses, ties)
    print(f'Team {team_id} has {wins} wins, {losses} losses, and {ties} ties.')
    total_games_played = wins + losses + ties
    print(f'Total Games Played: {total_games_played}')
    games_remaining = 16 - total_games_played
    if games_remaining == 0:
        print('The season is finished.')
    else:
        pass
    print(f'Total Games Remaining: {games_remaining}')
    winning_average = (wins/total_games_played) if total_games_played != 0 else 0
    print(f'The Winning Average is: {winning_average:.4f}')
    if (ties >= wins):
        print('The number of tied games are greater than or equal to the number of wins.')
    else:
        print('The number of tied games are not greater than or equal to the number of wins.')
    if ties >= losses:
        print('The number of tied games are greater than the number of losses.')
    else:
        print('The number of tied games are not greater than the number of losses.')
    wip_total = (wins + ties) - (3 * losses)
    if wip_total < 0:
        print(f'The Wip Total is: 0.')
    else:
        print(f'The Wip Total is: {wip_total}')
    Total_Number_of_Teams = len(int(team_id))
    print(f'The Total Number of Teams are {Total_Number_of_Teams}.')

但运行时收到了如下错误：

TypeError Traceback (most recent call last)
<ipython-input-101-f8b0a4f5d307> in <module>
----> 1 Total_Number_of_Teams = len(int(team_id))
2 print(f'The Total Number of Teams are {Total_Number_of_Teams}.')
TypeError: object of type 'int' has no len()

我试过用len()和count()函数，但还是遇到同样的错误，请问该怎么正确统计team_id里的团队总数？

错误原因分析 #

你现在的问题出在这行代码：

Total_Number_of_Teams = len(int(team_id))

team_id是每一行里的单个团队ID，把它转成整数后再用len()肯定会报错——因为整数类型没有长度属性，len()是用来统计序列（比如列表、字符串）的元素个数的，不是用来处理单个数值的。而且你把这段代码放在for循环里，每次循环都只处理一行数据，这样根本没法统计整个数据集里的团队总数。

解决方案 #

其实统计团队总数非常简单，你不需要在循环里处理，直接利用DataFrame的特性就能实现：

方法1：直接获取DataFrame的行数 #

因为每一行对应一个团队，所以团队总数就是整个DataFrame的行数，你可以用len(df)或者df.shape[0]来获取：

把原来循环里的那两行统计团队总数的代码删掉，然后在循环外面（比如读取完数据之后）加上：

total_teams = len(df)
# 或者 total_teams = df.shape[0]
print(f'The Total Number of Teams are {total_teams}.')

方法2：统计不重复的团队ID（如果有重复行的情况） #

如果你的数据里可能存在重复的团队ID（同一团队有多行数据），那你需要统计去重后的数量：

total_unique_teams = df[0].nunique()
print(f'The Total Number of Unique Teams are {total_unique_teams}.')

修改后的完整代码示例 #

import pandas as pd
df = pd.read_csv('https://raw.githubusercontent.com/avinashjairam/avinashjairam.github.io/master/question2_data%20.csv', header=None)

# 先统计团队总数，放在循环外面
total_teams = len(df)
print(f'The Total Number of Teams are {total_teams}.\n')

for index, rows in df.iterrows():
    team_info = rows.to_list()
    team_id = team_info[0]
    wins = team_info[1]
    losses = team_info[2]
    ties = team_info[3]
    print(team_id, wins, losses, ties)
    print(f'Team {team_id} has {wins} wins, {losses} losses, and {ties} ties.')
    total_games_played = wins + losses + ties
    print(f'Total Games Played: {total_games_played}')
    games_remaining = 16 - total_games_played
    if games_remaining == 0:
        print('The season is finished.')
    else:
        pass
    print(f'Total Games Remaining: {games_remaining}')
    winning_average = (wins/total_games_played) if total_games_played != 0 else 0
    print(f'The Winning Average is: {winning_average:.4f}')
    if (ties >= wins):
        print('The number of tied games are greater than or equal to the number of wins.')
    else:
        print('The number of tied games are not greater than or equal to the number of wins.')
    if ties >= losses:
        print('The number of tied games are greater than the number of losses.')
    else:
        print('The number of tied games are not greater than the number of losses.')
    wip_total = (wins + ties) - (3 * losses)
    if wip_total < 0:
        print(f'The Wip Total is: 0.')
    else:
        print(f'The Wip Total is: {wip_total}')
    print('---') # 分隔每个团队的信息，更清晰

这样修改后，就能正确统计出团队总数，而且不会再出现类型错误啦。

内容的提问来源于stack exchange，提问作者Shan456