On 7 January 2015 at 14:19, Victor Stinner
I never used the UNIX comm tool. I didn't know that it exists :-)
Can you maybe explain the purpose the tool/your function? Show an example.
The function has doctests included which may help. Basically, take 2 sorted lists (the Unix tool takes 2 sorted files of text), and merge them, preserving order, with each line marked as "only occurs in the first input", "only occurs in the second input" and "occurs in both inputs". So, for example, with inputs 1,1,2,4 and 1,3,4 we would get both: 1 first: 1 first: 2 second: 3 both: 4 The problem with difflib/diff is mainly that it does a *lot* more work than is needed - for sorted input, a fast single-pass algorithm is fine, whereas a general diff needs to work to find common subsequences. Paul