Hello all I'm trying to sort an array with two fields, but I'm getting a result that doesn't seem to make sense.
What I tried (first attempt): I have two 2-D arrays. I would like to sort one based on the sort of the other. I managed to do this with argsort. However, the fancy indexing required to get the sorted array using what argsort returned was very slow. I followed this example: http://www.scipy.org/Numpy_Example_List#head-9f8656795227e3c43e849c6c0435eee b32afd722 What I tried (second attempt): I created an array with two fields. I think/hope/expected that sorting the array would sort it on the first field in the dtype and then on the second. This is *much* faster than the fancy indexing approach. Code: import numpy as N print N.__version__ print dt = N.dtype([('aaa', N.float64), ('bbb', N.uint8)]) x = N.empty((2, 2), dt) xa = x[dt.names[0]] xa[:] = [[1.,2], [3.,4.]] xb = x[dt.names[1]] xb[:] = [[1, 2], [3, 4]] print 'before sort:' print x print x.sort(kind='quicksort') # other kinds not supported print 'after sort:' print x Output on my system: 1.0.dev3376 before sort: [[(1.0, 1) (2.0, 2)] [(3.0, 3) (4.0, 4)]] after sort: [[(2.0, 2) (1.0, 1)] [(4.0, 4) (3.0, 3)]] The already sorted array has been unsorted in some way. Any thoughts? Thanks! Regards, Albert ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
