pgr_cuthillMckeeOrdering
 Experimental¶
pgr_cuthillMckeeOrdering
— Returns the reverse CuthillMckee ordering of an undirected
graphs
Warning
Possible server crash
These functions might create a server crash
Warning
Experimental functions
They are not officially of the current release.
They likely will not be officially be part of the next release:
The functions might not make use of ANYINTEGER and ANYNUMERICAL
Name might change.
Signature might change.
Functionality might change.
pgTap tests might be missing.
Might need c/c++ coding.
May lack documentation.
Documentation if any might need to be rewritten.
Documentation examples might need to be automatically generated.
Might need a lot of feedback from the comunity.
Might depend on a proposed function of pgRouting
Might depend on a deprecated function of pgRouting
Availability
Version 3.4.0
New experimental function
Description¶
In numerical linear algebra, the CuthillMcKee algorithm (CM), named after Elizabeth Cuthill and James McKee, is an algorithm to permute a sparse matrix that has a symmetric sparsity pattern into a band matrix form with a small bandwidth.
The vertices are basically assigned a breadthfirst search order, except that at each step, the adjacent vertices are placed in the queue in order of increasing degree.
The main Characteristics are:
The implementation is for undirected graphs.
The bandwidth minimization problems are considered NPcomplete problems.
The running time complexity is: \(O(m log(m)V)\)
where \(V\) is the number of vertices,
\(m\) is the maximum degree of the vertices in the graph.
Signatures¶
(seq, node)
 Example:
Graph ordering of pgRouting Sample Data
SELECT * FROM pgr_cuthillMckeeOrdering(
'SELECT id, source, target, cost, reverse_cost FROM edges'
);
seq  node
+
1  13
2  14
3  2
4  4
5  1
6  9
7  3
8  8
9  5
10  7
11  12
12  6
13  11
14  17
15  10
16  16
17  15
(17 rows)
Parameters¶
Parameter 
Type 
Description 


Edges SQL as described below. 
Inner Queries¶
Edges SQL¶
Column 
Type 
Default 
Description 


ANYINTEGER 
Identifier of the edge. 


ANYINTEGER 
Identifier of the first end point vertex of the edge. 


ANYINTEGER 
Identifier of the second end point vertex of the edge. 


ANYNUMERICAL 
Weight of the edge ( 


ANYNUMERICAL 
1 
Weight of the edge (

Where:
 ANYINTEGER:
SMALLINT
,INTEGER
,BIGINT
 ANYNUMERICAL:
SMALLINT
,INTEGER
,BIGINT
,REAL
,FLOAT
Result columns¶
Returns set of (seq, node)
Column 
Type 
Description 



Sequence of the order starting from 1. 


New ordering in reverse order. 
See Also¶
The queries use the Sample Data network.
Indices and tables