I need help sorting a list...I just can't figure out how to sort a list
and then return a list with the index of the sorted items in the list
for example if the list I want to sort is [2,3,1,4,5]
I need [2,0,1,3,4] to be returned
Can someone help please.... 9 25837
custard_pie wrote: I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned http://aspn.activestate.com/ASPN/Coo.../Recipe/306862
Op 2005-05-03, custard_pie schreef <ck******@gmail.com>: I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned Can someone help please....
Something like this: lst = [2,3,1,4,5] inx = range(len(lst)) inx.sort(lambda x,y: lst[x] - lst[y]) print inx
[2, 0, 1, 3, 4]
--
Antoon Pardon
custard_pie wrote: I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned Can someone help please....
you need to pair up your values with the list indices, sort the list of
pairs then strip out the indices.
One way to do it: v = [2, 3, 1, 4, 5] import operator [ i for (i,j) in sorted(enumerate(v), key=operator.itemgetter(1))]
[2, 0, 1, 3, 4]
Le 3 May 2005 06:37:14 -0700, custard_pie a écrit : I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned Can someone help please....
If you have Python version 2.4 (or 2.4.1):
lst = [2,3,1,4,5]
import operator
sorted(enumerate(lst), key=operator.itemgetter(1))
[(2, 1), (0, 2), (1, 3), (3, 4), (4, 5)]
But *why* do you want the indices ? Most of the time dealing with the
indices is the wrong way in Python (perhaps the right way in FORTRAN :-)
On 3 May 2005 06:37:14 -0700, custard_pie <ck******@gmail.com> wrote: I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned spam = [2,3,1,4,5] list(index for index, item in sorted(enumerate(spam), key=lambda
item: item[1]))
[2, 0, 1, 3, 4]
--
Cheers,
Simon B, si***@brunningonline.net, http://www.brunningonline.net/simon/blog/
I'd map the values to their index in a dictionary, then sort the list,
and from the sorted list fetch all the indexes from the dictionary.
Something like : a = [2,3,1,4,5] b = list(a) b.sort() b
[1, 2, 3, 4, 5] indexDict = dict([ (value, index) for index, value in
enumerate(a)]) [indexDict[entry] for entry in b]
[2, 0, 1, 3, 4]
HTH
The code above uses enumerate, to shortcut getting the index. There may
be other shortcuts possible.
Regards,
Fuzzy http://www.voidspace.org.uk/python
Op 2005-05-03, Antoon Pardon schreef <ap*****@forel.vub.ac.be>: Op 2005-05-03, custard_pie schreef <ck******@gmail.com>: I need help sorting a list...I just can't figure out how to sort a list and then return a list with the index of the sorted items in the list for example if the list I want to sort is [2,3,1,4,5] I need [2,0,1,3,4] to be returned Can someone help please....
Something like this:
lst = [2,3,1,4,5] inx = range(len(lst)) inx.sort(lambda x,y: lst[x] - lst[y]) print inx [2, 0, 1, 3, 4]
Something a bit more usefull in general: lst = [2,3,1,4,5] inx = range(len(lst)) inx.sort(lambda x,y: cmp(lst[x],lst[y])) print inx
[2, 0, 1, 3, 4]
--
Antoon Pardon
Okay...THanks a lot everyone,.. Those codes really help....
Okay...THanks a lot everyone,.. Those codes are a real help.... This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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