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I have a 100GB CSV file. Looks something like this:
11,aa,gg,tt
ew,11,rggr,tr
And a second one which specifies substitutions (20,000 lines in this file):
gg,q
aaa,b
What I want to do is to go over every line in the first file and substitute the value of the third column if it appears in the second file (e.g. substitute gg with q in this case). Note that this is only if the whole string appears in the third column. So for the current example the result would be:
11,aa,q,tt
ew,11,rggr,tr
What would be a good way of achieving that?