pgr_primDD
— Catchament nodes using Prim’s algorithm.
Availability
Support
Using Prim algorithm, extracts the nodes that have aggregate costs less than
or equal to the value Distance
within the calculated minimum spanning tree.
The main Characteristics are:
Summary
pgr_prim(Edges SQL, root vid, distance)
pgr_prim(Edges SQL, root vids, distance)
RETURNS SET OF (seq, depth, start_vid, node, edge, cost, agg_cost)
pgr_primDD(Edges SQL, root vid, distance)
RETURNS SET OF (seq, depth, start_vid, node, edge, cost, agg_cost)
Example: | The Minimum Spanning Tree starting on vertex \(2\) with \(agg\_cost <= 3.5\) |
---|
SELECT * FROM pgr_primDD(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
2, 3.5
);
seq | depth | start_vid | node | edge | cost | agg_cost
-----+-------+-----------+------+------+------+----------
1 | 0 | 2 | 2 | -1 | 0 | 0
2 | 1 | 2 | 1 | 1 | 1 | 1
3 | 1 | 2 | 3 | 2 | 1 | 1
4 | 2 | 2 | 4 | 3 | 1 | 2
5 | 2 | 2 | 6 | 5 | 1 | 2
6 | 3 | 2 | 9 | 9 | 1 | 3
7 | 3 | 2 | 11 | 11 | 1 | 3
8 | 1 | 2 | 5 | 4 | 1 | 1
9 | 2 | 2 | 8 | 7 | 1 | 2
10 | 3 | 2 | 7 | 6 | 1 | 3
11 | 2 | 2 | 10 | 10 | 1 | 2
12 | 3 | 2 | 13 | 14 | 1 | 3
(12 rows)
pgr_primDD(Edges SQL, root vids, distance)
RETURNS SET OF (seq, depth, start_vid, node, edge, cost, agg_cost)
Example: | The Minimum Spanning Tree starting on vertices \(\{13, 2\}\) with \(agg\_cost <= 3.5\); |
---|
SELECT * FROM pgr_primDD(
'SELECT id, source, target, cost, reverse_cost FROM edge_table ORDER BY id',
ARRAY[13,2], 3.5
);
seq | depth | start_vid | node | edge | cost | agg_cost
-----+-------+-----------+------+------+------+----------
1 | 0 | 2 | 2 | -1 | 0 | 0
2 | 1 | 2 | 1 | 1 | 1 | 1
3 | 1 | 2 | 3 | 2 | 1 | 1
4 | 2 | 2 | 4 | 3 | 1 | 2
5 | 2 | 2 | 6 | 5 | 1 | 2
6 | 3 | 2 | 9 | 9 | 1 | 3
7 | 3 | 2 | 11 | 11 | 1 | 3
8 | 1 | 2 | 5 | 4 | 1 | 1
9 | 2 | 2 | 8 | 7 | 1 | 2
10 | 3 | 2 | 7 | 6 | 1 | 3
11 | 2 | 2 | 10 | 10 | 1 | 2
12 | 3 | 2 | 13 | 14 | 1 | 3
13 | 0 | 13 | 13 | -1 | 0 | 0
14 | 1 | 13 | 10 | 14 | 1 | 1
15 | 2 | 13 | 5 | 10 | 1 | 2
16 | 3 | 13 | 2 | 4 | 1 | 3
17 | 3 | 13 | 8 | 7 | 1 | 3
(17 rows)
Parameter | Type | Description |
---|---|---|
Edges SQL | TEXT |
SQL query described in Inner query. |
Root vid | BIGINT |
Identifier of the root vertex of the tree.
|
Root vids | ARRAY[ANY-INTEGER] |
Array of identifiers of the root vertices.
|
Distance | ANY-NUMERIC |
Upper limit for the inclusion of the node in the result.
|
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERIC: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT, NUMERIC |
Column | Type | Default | Description |
---|---|---|---|
id | ANY-INTEGER |
Identifier of the edge. | |
source | ANY-INTEGER |
Identifier of the first end point vertex of the edge. | |
target | ANY-INTEGER |
Identifier of the second end point vertex of the edge. | |
cost | ANY-NUMERICAL |
Weight of the edge (source, target)
|
|
reverse_cost | ANY-NUMERICAL |
-1 | Weight of the edge (target, source),
|
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT |
Returns SET OF (seq, depth, start_vid, node, edge, cost, agg_cost)
Column | Type | Description |
---|---|---|
seq | BIGINT |
Sequential value starting from \(1\). |
depth | BIGINT |
Depth of the
|
start_vid | BIGINT |
Identifier of the root vertex.
|
node | BIGINT |
Identifier of node reached using edge . |
edge | BIGINT |
Identifier of the
|
cost | FLOAT |
Cost to traverse edge . |
agg_cost | FLOAT |
Aggregate cost from start_vid to node . |
Indices and tables