Module « scipy.sparse.csgraph »

Fonction reverse_cuthill_mckee - module scipy.sparse.csgraph

Signature de la fonction reverse_cuthill_mckee

Description

reverse_cuthill_mckee.__doc__

    reverse_cuthill_mckee(graph, symmetric_mode=False)
    
    Returns the permutation array that orders a sparse CSR or CSC matrix
    in Reverse-Cuthill McKee ordering.  
    
    It is assumed by default, ``symmetric_mode=False``, that the input matrix 
    is not symmetric and works on the matrix ``A+A.T``. If you are 
    guaranteed that the matrix is symmetric in structure (values of matrix 
    elements do not matter) then set ``symmetric_mode=True``.
    
    Parameters
    ----------
    graph : sparse matrix
        Input sparse in CSC or CSR sparse matrix format.
    symmetric_mode : bool, optional
        Is input matrix guaranteed to be symmetric.

    Returns
    -------
    perm : ndarray
        Array of permuted row and column indices.
 
    Notes
    -----
    .. versionadded:: 0.15.0

    References
    ----------
    E. Cuthill and J. McKee, "Reducing the Bandwidth of Sparse Symmetric Matrices",
    ACM '69 Proceedings of the 1969 24th national conference, (1969).

    Examples
    --------
    >>> from scipy.sparse import csr_matrix
    >>> from scipy.sparse.csgraph import reverse_cuthill_mckee

    >>> graph = [
    ... [0, 1 , 2, 0],
    ... [0, 0, 0, 1],
    ... [2, 0, 0, 3],
    ... [0, 0, 0, 0]
    ... ]
    >>> graph = csr_matrix(graph)
    >>> print(graph)
      (0, 1)	1
      (0, 2)	2
      (1, 3)	1
      (2, 0)	2
      (2, 3)	3

    >>> reverse_cuthill_mckee(graph)
    array([3, 2, 1, 0], dtype=int32)