Efficient Rank Ordering of Nested Lists

[beginner]

On Aug 2, 8:20 pm, "pablo.mitch... at gmail.com"
<pablo.mitch... at gmail.com> wrote:
> A naive approach to rank ordering (handling ties as well) of nested
> lists may be accomplished via:
>
>    def rankLists(nestedList):
>       def rankList(singleList):
>           sortedList = list(singleList)
>           sortedList.sort()
>           return map(sortedList.index, singleList)
>       return map(rankList, nestedList)
>
>    >>> unranked = [ [ 1, 2, 3, 4, 5 ], [ 3, 1, 5, 2, 4 ], [ -1.1, 2.2,
> 0, -1.1, 13 ] ]
>    >>> print rankLists(unranked)
>
>    [[0, 1, 2, 3, 4], [2, 0, 4, 1, 3], [0, 3, 2, 0, 4]]
>
> This works nicely when the dimensions of the nested list are small.
> It is slow when they are big.  Can someone suggest a clever way to
> speed it up?

Indexing the sorted list with a dictionary will speed it up a little.