scipy.sparse.csgraph.
reverse_cuthill_mckee#
- scipy.sparse.csgraph.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:
- graphsparse array or matrix
- Input sparse in CSC or CSR sparse array or matrix format. 
- symmetric_modebool, optional
- Is input matrix guaranteed to be symmetric. 
 
- Returns:
- permndarray
- Array of permuted row and column indices. 
 
 - Notes - Added in version 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_array >>> 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_array(graph) >>> print(graph) <Compressed Sparse Row sparse array of dtype 'int64' with 5 stored elements and shape (4, 4)> Coords Values (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)