pgr_drivingDistance - Deprecated Signature¶
Warning
This function signature is deprecated!!!
- That means it has been replaced by new signature(s)
- This signature is no longer supported, and may be removed from future versions.
- All code that use this function signature should be converted to use its replacement pgr_drivingDistance.
Name¶
pgr_drivingDistance - Returns the driving distance from a start node.
Synopsis¶
This function computes a Dijkstra shortest path solution them extracts the cost to get to each node in the network from the starting node. Using these nodes and costs it is possible to compute constant drive time polygons. Returns a set of pgr_costResult (seq, id1, id2, cost) rows, that make up a list of accessible points.
pgr_costResult[] pgr_drivingDistance(text sql, integer source, double precision distance,
boolean directed, boolean has_rcost);
Description¶
sql: | a SQL query, which should return a set of rows with the following columns: SELECT id, source, target, cost [,reverse_cost] FROM edge_table
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source: | int4 id of the start point |
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distance: | float8 value in edge cost units (not in projection units - they might be different). |
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directed: | true if the graph is directed |
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has_rcost: | if true, the reverse_cost column of the SQL generated set of rows will be used for the cost of the traversal of the edge in the opposite direction. |
Returns set of pgr_costResult[]:
seq: | row sequence |
---|---|
id1: | node ID |
id2: | edge ID (this is probably not a useful item) |
cost: | cost to get to this node ID |
Warning
You must reconnect to the database after CREATE EXTENSION pgrouting. Otherwise the function will return Error computing path: std::bad_alloc.
History
- Renamed in version 2.0.0
Examples¶
- Without reverse_cost
- With reverse_cost
SELECT * FROM pgr_drivingDistance(
'SELECT id::INTEGER, source::INTEGER, target::INTEGER, cost FROM edge_table',
7, 1.5, false, false
) ;
NOTICE: Deprecated function
seq | id1 | id2 | cost
-----+-----+-----+------
0 | 7 | -1 | 0
1 | 8 | 6 | 1
(2 rows)
SELECT * FROM pgr_drivingDistance(
'SELECT id::INTEGER, source::INTEGER, target::INTEGER, cost, reverse_cost FROM edge_table',
7, 1.5, true, true
) ;
NOTICE: Deprecated function
seq | id1 | id2 | cost
-----+-----+-----+------
0 | 7 | -1 | 0
1 | 8 | 6 | 1
(2 rows)
The queries use the Sample Data network.
See Also¶
- pgr_drivingDistance
- pgr_alphaShape - Alpha shape computation
- pgr_pointsAsPolygon - Polygon around set of points