Hi, On Thu, Aug 2, 2012 at 3:43 PM, Nicole Stoffels <nicole.stoff...@forwind.de>wrote:
> Dear all, > > I have a two-dimensional array: > > a = array([[1,2,3],[0,2,1],[5,7,8]]) > > I want to reorder it by the last column in descending order, so that I get: > > b =array([[5, 7, 8],[1, 2, 3],[0, 2, 1]]) > Perhaps along the lines: In []: a Out[]: array([[1, 2, 3], [0, 2, 1], [5, 7, 8]]) In []: ndx= a[:, 2].argsort() In []: a[ndx[::-1], :] Out[]: array([[5, 7, 8], [1, 2, 3], [0, 2, 1]]) > > What I did first is the following, which reorders the array in ascending > order (I found that method in the internet): > > b = array(sorted(a, key=lambda new_entry: new_entry[2])) > b = array([[0, 2, 1],[1, 2, 3],[5, 7, 8]]) > > But I want it just the other way arround. So I did the following > afterwards which results in an array only containing zeros: > b_indices = b.argsort() > b_matrix = b[b_indices[::-1]] > new_b = b_matrix[len(b_matrix)-1] > > Is there an easy way to reorder it? Or is there at least a complicated > way which produces the right output? > > I hope you can help me! Thanks! > My 2 cents, -eat > > Best regards, > > Nicole > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
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