Posted By: Anonymous
This seems like it should be pretty trivial, but I am new at Python and want to do it the most Pythonic way.
I want to find the index corresponding to the n’th occurrence of a substring within a string.
There’s got to be something equivalent to what I WANT to do which is
How can you achieve this in Python?
Mark’s iterative approach would be the usual way, I think.
Here’s an alternative with string-splitting, which can often be useful for finding-related processes:
def findnth(haystack, needle, n): parts= haystack.split(needle, n+1) if len(parts)<=n+1: return -1 return len(haystack)-len(parts[-1])-len(needle)
And here’s a quick (and somewhat dirty, in that you have to choose some chaff that can’t match the needle) one-liner:
'foo bar bar bar'.replace('bar', 'XXX', 1).find('bar')