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scipy.sparse.

# triu

scipy.sparse.triu(A, k=0, format=None)

  Return the upper triangular portion of a sparse array or matrix

  Returns the elements on or above the k-th diagonal of A.

    - k = 0 corresponds to the main diagonal

    - k > 0 is above the main diagonal

    - k < 0 is below the main diagonal

  Parameters:
    A dense or sparse array or matrix

      Matrix whose upper trianglar portion is desired.

    k integer optional

      The bottom-most diagonal of the upper triangle.

    format string

      Sparse format of the result, e.g. format=”csr”, etc.

  Returns:
    L sparse array or matrix

      Upper triangular portion of A in sparse format. Sparse array if A is a sparse array, otherwise matrix.

  See also

  `tril`

    lower triangle in sparse format

  Examples

      >>> from scipy.sparse import csr_array, triu
      >>> A = csr_array([[1, 2, 0, 0, 3], [4, 5, 0, 6, 7], [0, 0, 8, 9, 0]],
      ...                dtype='int32')
      >>> A.toarray()
      array([[1, 2, 0, 0, 3],
             [4, 5, 0, 6, 7],
             [0, 0, 8, 9, 0]], dtype=int32)
      >>> triu(A).toarray()
      array([[1, 2, 0, 0, 3],
             [0, 5, 0, 6, 7],
             [0, 0, 8, 9, 0]], dtype=int32)
      >>> triu(A).nnz
      8
      >>> triu(A, k=1).toarray()
      array([[0, 2, 0, 0, 3],
             [0, 0, 0, 6, 7],
             [0, 0, 0, 9, 0]], dtype=int32)
      >>> triu(A, k=-1).toarray()
      array([[1, 2, 0, 0, 3],
             [4, 5, 0, 6, 7],
             [0, 0, 8, 9, 0]], dtype=int32)
      >>> triu(A, format='csc')
      <Compressed Sparse Column sparse array of dtype 'int32'
          with 8 stored elements and shape (3, 5)>