sorting list of indices

How do I sort a list of indices by what they'r开发者_JAVA百科e pointing to in python?

I have

 indices = list(range(len(mylist)))

I want to sort the indices so that if a precedes b in indices then mylist[a] > mylist[b].

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indicies.sort(lambda x,y:mylist[x]-mylist[y])

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Also, let me add the following snippet as an answer, using the information provided in your original question...

I want to sort the indices so that if a precedes b in indices then mylist[a] > mylist[b].

...and the additional info you have in your comment

Also, what if mylist is a list of numpy floats?

Then you can simply do:

In [2]: import numpy

In [3]: a = numpy.asarray([-1, 2.73, 15.827, -8.48, 9, 13, 15, 3.22, 0, -1, 1])

In [4]: indices = a.argsort()[::-1]
Out[4]: array([ 2,  6,  5,  4,  7,  1, 10,  8,  9,  0,  3])

In [5]: a[indices]
Out[5]: 
array([ 15.827,  15.   ,  13.   ,   9.   ,   3.22 ,   2.73 ,   1.   ,
     0.   ,  -1.   ,  -1.   ,  -8.48 ])

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Python 2.6+, most elegant answer:

indices.sort(key = lambda x:mylist[x], reverse = True)