sort array return index in np code example

Example 1: python argsort a list

a=list((1, 2, 3, -20))
sorted(range(len(a)), key=a.__getitem__)

output:
[3, 0, 1, 2]

Example 2: python argsort

def g(seq):
    # http://stackoverflow.com/questions/3382352/equivalent-of-numpy-argsort-in-basic-python/3383106#3383106
    #lambda version by Tony Veijalainen
    return [x for x,y in sorted(enumerate(seq), key = lambda x: x[1])]