strcmp for python or how to sort substrings efficiently (without copy) when building a suffix array

Question

Here\'s a very simple way to build an suffix array from a string in python:

def sort_offsets(a, b):
    return cmp(content[a:], content[b:])

content = \"foobar          


        

Answer 1

I don't know if there's a fast way to compare substrings, but you can make your code much faster (and simpler) by using key instead of cmp:

suffix_array.sort(key=lambda a: content[a:])

This will create the substring just once for each value of a.

Edit: A possible downside is that it will require O(n^2) memory for the substrings.