On Wed, Jan 16, 2013 at 9:30 AM, Mads Ipsen <madsip...@gmail.com> wrote: > Hi, > > Thanks everybody for all the answers that make perfect sense when axis=0. > > Now suppose I want to sort the array in such a way that each row is sorted > individually. Then I suppose I should do this: > > from numpy import * > > > v = array([[4,3], > [1,12], > [23,7], > [11,6], > [8,9]]) > idx = argsort(v, axis=1) > > idx is then > > [[1 0] > [0 1] > [1 0] > [1 0] > [0 1]] > > which makes sense, since these are the indices in an order that would sort > each row. But when I try > > a[idx, variuos_additional_arguments] > > I just get strange results. Anybody that can point me towards the correct > solution.
Please have a look at the documentation again. If idx has indices for the second axis, you need to put it into the second place. http://docs.scipy.org/doc/numpy/user/basics.indexing.html#indexing-multi-dimensional-arrays http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html#advanced-indexing [~] |4> idx0 = np.arange(v.shape[0])[:,np.newaxis] [~] |5> idx0 array([[0], [1], [2], [3], [4]]) [~] |7> v[idx0, idx] array([[ 3, 4], [ 1, 12], [ 7, 23], [ 6, 11], [ 8, 9]]) -- Robert Kern _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
