Python 脚本到 append 数据在一个 csv 到另一个 Z628CB5675FF524F3E719BFEAAZE8 比较后

Question

I have a script which compares 2 csv files and outputs the data to a new CSV file. I am looking for help to be able to append the data in the new output file to the allhistory file in thee same code. Anyone suggest what to use?

import csv

with open('allhistory.csv', 'r') as t1, open('filewithnewdata.csv', 'r') as t2:
    fileone = t1.readlines()
    filetwo = t2.readlines()

with open('update.csv', 'w') as outFile:
    for line in filetwo:
        if line not in fileone:
            outFile.write(line)

Answer 1

You could keep a list of the lines that you write to update.csv and then write the contents of fileone followed by the updates, overwriting the existing file. For example:

with open('allhistory.csv', 'r') as t1, open('filewithnewdata.csv', 'r') as t2:
    fileone = t1.readlines()
    filetwo = t2.readlines()

matches = []

with open('update.csv', 'w') as outFile:
    for line in filetwo:
        if line not in fileone:
            matches.append(line)
            outFile.write(line)    

with open('allhistory.csv', 'w') as outFile:
    outFile.write(''.join(fileone).strip() + '\n' + ''.join(matches))

Note, you are just comparing whole lines in the file, you are not currently using csv to split each line into values.