如何從csv檔案中讀取名稱和等級并將它們的平均值寫入另一個csv檔案？

我是 python 的初學者，我想從一個 csv 檔案中讀取一些名稱和成績，并在另一個 csv 檔案中寫入成績的平均值。我可以從 csv 檔案中讀取成績，但我不知道如何在另一個 csv 檔案中寫入均值 :(（有沒有辦法在沒有像 Pandas 這樣的庫的幫助下撰寫此代碼？）

import csv
from os import name
from statistics import mean

with open(input_file_name) as f:
    reader = csv.reader(f)
    for row in reader:
        name = row[0]
        grades = row[1:]
        these_grades1 = list()
        for grade in grades:
            these_grades1.append(int(grade))
            mean1 = mean(these_grades1)

        #print(name,float(mean1))

    with open(output_file_name, 'w' , newline='') as new_f:
        writer = csv.writer(new_f)

        for row in reader:
            writer.writerow("%s,%s" % (name, float(mean1)))

        new_f.close()

名稱和等級：

marie,5,7,3,15
harry,3,9,4,20,9,1,8,16,0,5,2,4,7,2,1
john,19,10,19,6,8,14,3
sara,0,5,20,14
david,13,2,5,1,3,10,12,4,13,17,7,7
robert,1,9
james,0,16,16,13,19,2,17,8

正確的輸出：

marie,7.5
harry,6.066666666666666
john,11.285714285714286
sara,9.75
david,7.833333333333333
robert,5.0
james,11.375

uj5u.com熱心網友回復：

代碼有幾個問題：

• 您不斷覆寫mean1，這意味著每次讀取新學生時都會丟失每個學生的平均值。使用串列跟蹤已計算的均值（這是result在我的代碼中）。
• 不知道為什么reader在列印輸出時迭代
• writerow 接受一個串列作為輸入，而不是一個字串（如果你使用字串，它會列印得非常奇怪）

這是一個固定版本：

import csv
from os import name

result = []
with open(input_file_name) as f:
    reader = csv.reader(f)
    for row in reader:
        name = row[0]
        grades = row[1:]
        for i, grade in enumerate(grades):
            grades[i] = int(grade)
        mean = sum(grades)/len(grades)
        result.append([name, mean])

with open(output_file_name, 'w' , newline='') as new_f:
    writer = csv.writer(new_f)
    for row in result:
        writer.writerow(row)

您也可以在沒有串列的情況下執行此操作：

import csv
from os import name

with open(input_file_name) as f, open(output_file_name, 'w' , newline='') as new_f:
    reader = csv.reader(f)
    writer = csv.writer(new_f)
    for row in reader:
        name = row[0]
        grades = row[1:]
        for i, grade in enumerate(grades):
            grades[i] = int(grade)
        mean = sum(grades)/len(grades)
        writer.writerow([name, mean])

uj5u.com熱心網友回復：

這會給你適當的結果 https://replit.com/@arvindDhakad/SilkyMarriedCleaninstall#main.py

import csv
from os import name
from statistics import mean

#open both file here
with open(input_file_name) as f, open(output_file_name, 'w' , newline='') as new_f:
    #initialize writer 
    writer = csv.writer(new_f)
    
    #initialize reader
    reader = csv.reader(f)

    for row in reader:
        name = row[0]
        grades = row[1:]
        these_grades1 = list()
        for grade in grades:
            these_grades1.append(int(grade))
            # you don't need to calculate mean here 
        
        # calculate mean
        mean1 = mean(these_grades1)

        # write to file
        writer.writerow([name, float(mean1)])

更多pythonic版本：

import csv
from statistics import mean

with open(input_file_name) as f, open(output_file_name, 'w',
                                      newline='') as new_f:
    #initialize writer
    writer = csv.writer(new_f)

    #initialize reader
    reader = csv.reader(f)
    writer.writerows([[row[0], mean(map(int, row[1:]))] for row in reader])

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