Most efficient way to compare two near identical CSV's in Python?
An efficient way would be to read each line from the first file(with less number of lines) and save in an object like Set or Dictionary, where you can access using O(1) complexity. 
And then read lines from the second file and check if it exists in the Set or not.
I have two CSV's, each with about 1M lines, n number of columns, with identical columns. I want the most efficient way to compare the two files to find where any difference may lie. I would prefer to parse this data with Python rather than use any excel-related tools.