From: Guillaume Bloss <elysah@...>
Date: 2011-10-05T21:34:40+09:00
Subject: Best way to compare lines in 2 files

Hi everybody,

I have an issue :

I have 2 list in 2 separate files
I call them 1st file = old file, 2nd file = new file
They are similar, except there is some lines added and some lines
removed in both files, and I only want to keep : lines common in both
files and line only existing in my 2nd file.

My first solution is to read the 2nd file, compare each lines with each
lines of the 1st file see if I fond it and if not, save it in a 3rd file
to list all lines I have to remove in my 2nd file.

Then I will read my 2nd file and compare each line with each lines of my
3rd file, if it does not exist, I write the line in a 4th file (the
final)

I'm not sure if this is the quickest and best method, maybe something
faster exist.
I also assume there is a fast method, with high memory usage and a
slower but with low memory usage.
My files are excel sheet exported in CSV files, but with something like
40k lines each

So if someone have clues to help me I would be grateful.

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