如何比较两个 csv 文件并打印所有差异

Question

I have two csv files (old.csv and new.csv) with lot of data in them. Both the csv files have same data but ordering can be different for each row. old.csv file act as the source file. I am tyring to compare both the csv files to see if any row is missing or any new row is there.

• Compare old.csv with new.csv and see if any row is missing in new.csv or any new row is present in new.csv . Each row should exactly match in both the csv's.

Below code I have only checks for new row in new.csv which is not present in old.csv but how can we also check for all other things.

with open('old.csv', 'r') as t1, open('new.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)

Basically both old.csv and new.csv files should exactly match with everything like content (each row), number of entries and other things. There should not be any difference between these two files.

Answer 1

You could consider using difflib for this, but it will have the same limitations as command-line diff. It can report a line as "new" when it's merely moved.

Assuming order isn't important, the set-based approach is probably what you need.