Impedance obsolete dijkstra OD

network-functions obsolete: Dijkstra OD

Starting from GeoDMS version 7.115, a new set of dijkstra functions replace the ones described below.
The documentation of the old versions is still available for backward compatibility,
the old functions will become obsolete in future versions.

syntax

  • dijkstra_od(link_impedance,link_node1_rel, lin_node2_rel, originloc_node_rel, originloc_impedance, originloc_origin_rel,destloc_node, destloc_impedance, destloc_dest_rel)

  • dijkstra_od_maxdist(link_impedance,link_node1_rel, lin_node2_rel,originloc_node_rel, originloc_impedance, originloc_origin_rel,destloc_node, destloc_impedance, destloc_dest_rel,origin_impedance_max)

definition

The dijkstra_od functions apply the dijkstra algorithm to calculate the shortest network impedance from a set of origin points to a set of destination points.The result is an O(rigin) D(estination) matrix, in Dutch: Herkomst/Bestemmingsmatrix.

  • dijkstra_od(link_impedance,link_node1_rel, lin_node2_rel,originloc_node_rel, originloc_impedance, originloc_origin_rel,destloc_node, destloc_impedance, destloc_dest_rel)

or

  • dijkstra_od_maxdist(link_impedance,link_node1_rel, lin_node2_rel,originloc_node_rel, originloc_impedance, originloc_origin_rel,destloc_node, destloc_impedance, destloc_dest_rel,origin_impedance_max)

with:

  • link_impedance: a data-item with the impedance of the links of a linkset; link_node1_rel: a relation to the first node of a link set;
  • link_node2_rel: a relation to the last node of a link set;

  • originloc_node_rel: a relation to the origin nodes;
  • originloc_impedance: start impedance for each origin, from the startpoint to the startnode;
  • originloc_origin_rel: a relation to each origin;

  • destloc_node: a relation to destination node;
  • destloc_impedance: end impedance for each destination, from the endnode to the end point;
  • destloc_dest_rel: a relation to each destination;

  • origin_impedance_max: maximum impedance for the resulting sparse matrix of od_pairs

description

To apply any dijkstra function, first configure a nodeset (based on the origin and destination points) and a linkset (based on the segments in an arc set, usually with roads).

These variants of the dijkstra function result in a new domain-unit with a subitem called impedance. This subitem indicates the impedance from each origin point towards each destination point. The values-unit is the values unit of the three impedance argument. The cardinality of the new domain unit is the product of the cardinality of the origin and destination domain units.

The relations the to origin(originn_nr) and destination(destination_nr) domain units can be configured with the expression presented in the example.

applies to

  • attribute impedance_link, impedance_origin and impedance_destination with float32 or float64 value-type
  • attributes F1, F2, nr_originnode, nr_destnode, indexnumber_origin and indexnumber_destination with uint32 value type

conditions

  1. The domain unit of arguments impedance_link, F1 and F2 must match.
  2. The domain unit of arguments nr_originnode, impedance_origin and indexnumber_origin must match.
  3. The domain unit of arguments nr_destnode, impedance_destination and indexnumber_destination must match.
  4. The values unit of arguments impedance_link, impedance_origin and impedance_destination must match.

since version

5.95

example

unit<uint32> od := dijkstra_od(dist, F1, F2
       , nr_OrgNode,  const(0, ODomain, m), id(ODomain)
       , nr_DestNode, const(0, DDomain, m), id(DDomain)
   );
// replace this obsolete syntax to

unit<uint32> odd := dijkstra_m(
      'bidirectional;startPoint(Node_rel);endPoint(Node_rel);od:impedance
      ,OrgZone_rel,DstZone_rel
     , dist
     , F1
     , F2
     , network/nr_OrgNode
     , network/nr_DestNode
   )
{
   attribute<ODomain> originn_nr      :=     id(OD) / #DDomain;
   attribute<DDomain> destination_rel := mod(id(OD) , #DDomain);
}
dist F1 F2
713.44 9 10
907.33 0 3
1913.96 3 19
1907.31 19 26
.. .. ..
.. .. ..

domain Linkset, nr of rows = 34

nr_orgnode
22
17
14
29
8

domain ODomain, nr of rows = 5

nr_destnode
22
13
6
30

domain Destination, nr of rows = 4

Impedance origin_nr destination_nr
0 0 0
5093.28 0 1
5596.24 0 2
5410 0 3
5896.14 1 0
1383.17 1 1
5272.83 1 2
5086.39 1 3
4901.69 2 0
3775.21 2 1
1393.9 2 2
4091.94 2 3
6181.57 3 0
5055.09 3 1
5558.26 3 2
1457.7 3 3
5956.03 4 0
1443.05 4 1
5332.71 4 2
5146.27 4 3

domain OD, nr of rows = 20