使用python将另一列添加到CSV文件 [英] Adding another column to a CSV file w/ python

问题描述

我希望将另一列添加到带python的CSV文件中.

I am looking to add another column to a CSV file w/ python.

file1是Date.csv具有格式

file1 is Date.csv has format

ID, Date
0,"Jan 22, 2016"
1,"Jan 21, 2016"
2,"Jan 20, 2016"
3,"Jan 19, 2016"

和

file2是Price.csv

file2 is Price.csv

ID, Price
0,27.89
1,26.80
2,26.78
3,26.00

我想要的输出是(在Date.csv中)

My desired output is (in Date.csv)

ID, Date
0,"Jan 22, 2016", 27.89
1, "Jan 21, 2016", 26.80
2, "Jan 20, 2016", 26.78
3, "Jan 19, 2016", 26.00

但是我要返回的是重复价格

but what I'm returning is the price repeating

0,27.89,27.89
1,26.80,26.80
2,26.78,26.78
3,26.00,26.00

我的程序如下

import csv

with open('C:/Users/User/OneDrive/Documents/Price.csv','r') as csvinput:
    with open('C:/Users/User/OneDrive/Documents/Date.csv', 'w') as csvoutput:
        writer = csv.writer(csvoutput, lineterminator='\n')
        reader = csv.reader(csvinput)

        all = []
        row = next(reader)

        for row in reader:
            row.append(row[1])
            all.append(row)

        writer.writerows(all)

感谢一些指导，欢呼

推荐答案

您不能只将一列写入现有文件.最好的选择是创建一个新文件.如果数据符合两个文件的顺序，则只需将它们压缩并写出更新的字典即​​可:

You can't just write a single column into an existing file. Best option is create a new file. If the data is in order for both files then you can simply zip them up and write the updated dictionary out:

with open('C:/Users/User/OneDrive/Documents/Date.csv') as file1, \
     open('C:/Users/User/OneDrive/Documents/Price.csv') as file2, \
     open('C:/Users/User/OneDrive/Documents/Output.csv', 'w') as output:
    reader1 = csv.DictReader(file1)
    reader2 = csv.DictReader(file2)
    writer = csv.DictWriter(output, ['ID', 'Date', 'Price'])
    writer.writeheader()  # Optional if you want the header

    for row1, row2 in zip(reader1, reader2):
        row1.update(row2)
        writer.writerow(row1)

熊猫也是另一个选择:

import pandas as pd
file1 = pd.read_csv('Data.csv', index_col='ID')
file2 = pd.read_csv('Price.csv', index_col='ID')
pd.concat([file1,file2], axis=1).to_csv('Output.csv')

输出:

ID,Date,Price
0,"Jan 22, 2016",27.89
1,"Jan 21, 2016",26.80
2,"Jan 20, 2016",26.78
3,"Jan 19, 2016",26.00

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