Find the index of the n'th item in a list

Question

I want to find the index of the n\'th occurrence of an item in a list. e.g.,

x=[False,True,True,False,True,False,True,False,False,False,True,False,True]
         


        

Answer 1

I can't say for certain that this is the fastest way, but I imagine it'd be pretty good:

i = -1
for j in xrange(n):
    i = x.index(True, i + 1)

The answer is i.