how to return index of a sorted list? [duplicate]

You can use the python sorting functions' key parameter to sort the index array instead.

>>> s = [2, 3, 1, 4, 5, 3]
>>> sorted(range(len(s)), key=lambda k: s[k])
[2, 0, 1, 5, 3, 4]
>>> 

You can do this with numpy's argsort method if you have numpy available:

>>> import numpy
>>> vals = numpy.array([2,3,1,4,5])
>>> vals
array([2, 3, 1, 4, 5])
>>> sort_index = numpy.argsort(vals)
>>> sort_index
array([2, 0, 1, 3, 4])

If not available, taken from this question, this is the fastest method:

>>> vals = [2,3,1,4,5]
>>> sorted(range(len(vals)), key=vals.__getitem__)
[2, 0, 1, 3, 4]