两个csv文件的比较和输出有什么不同？

Question

我正在比较两个 csv 文件，但 update.csv 文件与 new.csv 相同

import csv

with open('old.csv', 'r') as t1:
    old_csv = t1.readlines()

with open('new.csv', 'r') as t2:
    new_csv = t2.readlines()

with open('update.csv', 'w') as out_file:
        line_in_new = 0
        line_in_old = 0
        while line_in_new < len(new_csv) and line_in_old < len(old_csv):
            if old_csv[line_in_old] != new_csv[line_in_new]:
                out_file.write(new_csv[line_in_new])
            else:
        line_in_old += 1
    line_in_new += 1

我希望输出与示例相同。

示例：

输入：

旧的.csv

a,b,c
1,2,3
4,5,6
8,9,9

新的.csv

a,b,c
1,2,3
5,6,7
8,9,7

输出：

更新.csv

4,5,6,deleted
5,6,7,new added 
8,9,9,change

请帮我找出update.csv的唯一区别

Answer 1

使用 pandas 的解决方案：

import pandas as pd

df1 = pd.read_csv('old.csv')
df2 = pd.read_csv('new.csv')

df1['flag'] = 'old'
df2['flag'] = 'new'

df = pd.concat([df1, df2])

dups_dropped = df.drop_duplicates(df.columns.difference(['flag']), keep=False)
dups_dropped.to_csv('update.csv', index=False)

输入：

old.csv

a,b,c
1,2,3
4,5,6

new.csv

a,b,c
1,2,3
5,6,7

输出：

update.csv

a,b,c,flag
4,5,6,old
5,6,7,new