# numpy.triu_indices_from

numpy.triu_indices_from(arr, k=0)

  Return the indices for the upper-triangle of arr.

  See `triu_indices` for full details.

  Parameters:
    arr ndarray, shape(N, N)

      The indices will be valid for square arrays.

    k int, optional

      Diagonal offset (see `triu` for details).

  Returns:
    triu_indices_from tuple, shape(2) of ndarray, shape(N)

      Indices for the upper-triangle of arr.

  See also

  `triu_indices`, `triu`, `tril_indices_from`

  Notes

  New in version 1.4.0.

  Examples

  Create a 4 by 4 array.

      >>> a = np.arange(16).reshape(4, 4)
      >>> a
      array([[ 0,  1,  2,  3],
             [ 4,  5,  6,  7],
             [ 8,  9, 10, 11],
             [12, 13, 14, 15]])

  Pass the array to get the indices of the upper triangular elements.

      >>> triui = np.triu_indices_from(a)
      >>> triui
      (array([0, 0, 0, 0, 1, 1, 1, 2, 2, 3]), array([0, 1, 2, 3, 1, 2, 3, 2, 3, 3]))

      >>> a[triui]
      array([ 0,  1,  2,  3,  5,  6,  7, 10, 11, 15])

  This is syntactic sugar for triu_indices().

      >>> np.triu_indices(a.shape[0])
      (array([0, 0, 0, 0, 1, 1, 1, 2, 2, 3]), array([0, 1, 2, 3, 1, 2, 3, 2, 3, 3]))

  Use the k parameter to return the indices for the upper triangular array from the k-th diagonal.

      >>> triuim1 = np.triu_indices_from(a, k=1)
      >>> a[triuim1]
      array([ 1,  2,  3,  6,  7, 11])