On 6/26/07, Tom Denniston <[EMAIL PROTECTED]> wrote:
In [1]: intArr1 = numpy.array([ 0, 1, 2,-2,-1, 5,-5,-5]) In [2]: intArr2 = numpy.array([1,1,1,2,2,2,3,4]) In [3]: charArr = numpy.array(['a','a','a','b','b','b','c','d']) Here I sort two int arrays. As expected intArr2 dominates intArr1 but the items with the same intArr2 values are sorted forwards according to intArr1 In [6]: numpy.lexsort((intArr1, intArr2)) Out[6]: array([0, 1, 2, 3, 4, 5, 6, 7]) This, however, looks like a bug to me. Here I sort an int array and a str array. As expected charArray dominates intArr1 but the items with the same charArray values are sorted *backwards* according to intArr1 In [5]: numpy.lexsort((intArr1, charArr)) Out[5]: array([2, 1, 0, 5, 4, 3, 6, 7]) Is this a bug or am I missing something?
Looks like a bug. In [12]: numpy.argsort([charArr], kind='m') Out[12]: array([[2, 1, 0, 5, 4, 3, 6, 7]]) In [13]: numpy.argsort([intArr2], kind='m') Out[13]: array([[0, 1, 2, 3, 4, 5, 6, 7]]) Both of these are stable sorts, and since the elements are in order should return [[0, 1, 2, 3, 4, 5, 6, 7]]. Actually, I think they should return [0, 1, 2, 3, 4, 5, 6, 7], I'm not sure why the returned array is 2D and I suspect that is a bug also. As to why the string array sorts incorrectly, I am not sure. It could be that the sort isn't stable, there could be a stride error, or the comparison is returning wrong values. My bet is on the first being the case. Please file a ticket on this. Chuck
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