如何从csv文件中读取姓名和成绩，并在另一个csv文件中写入平均值?

Question

我是python的初学者，我想从csv文件中读取一些名称和成绩，并在另一个csv文件中写入成绩的平均值。我可以从csv文件中读取分数，但我不知道如何在另一个csv文件中编写方法:((有没有办法在没有像pandas这样的库的帮助下编写这段代码?)

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()

姓名和等级:

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

正确的输出:

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

Answer 1

这将为您提供合适的结果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python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])

Answer 2

代码有一些错误:

• 您继续覆盖mean1，这意味着每次读取新学生时都会丢失每个学生的平均值。使用列表来跟踪已经计算的平均值(这是我代码中的result)。
• 不确定为什么在打印输出
时迭代reader
• writerow接受列表作为输入，而不是字符串(如果使用字符串，它将非常奇怪地打印)

这是一个固定的版本:

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)

你也可以这样做，不需要列表:

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])