[Numpy-discussion] another little index puzzle
Robert Kern
robert.kern@gmail....
Mon Jan 21 07:50:53 CST 2013
On Mon, Jan 21, 2013 at 2:41 PM, Neal Becker <ndbecker2@gmail.com> wrote:
> I have an array to be used for indexing. It is 2d, where the rows are all the
> permutations of some numbers. So:
>
> array([[-2, -2, -2],
> [-2, -2, -1],
> [-2, -2, 0],
> [-2, -2, 1],
> [-2, -2, 2],
> ...
> [ 2, 1, 2],
> [ 2, 2, -2],
> [ 2, 2, -1],
> [ 2, 2, 0],
> [ 2, 2, 1],
> [ 2, 2, 2]])
>
> Here the array is 125x3
>
> I want to select all the rows of the array in which all the 3 elements are
> equal, so I can remove them. So for example, the 1st and last row.
all_equal_mask = np.logical_and.reduce(arr[:,1:] == arr[:,:-1], axis=1)
some_unequal = arr[~all_equal_mask]
--
Robert Kern
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