Trace_back

network-functions trace_back

syntax

  • trace_back(F1, F2, dijkstra/traceback, capacity)

definition

trace_back(F1, F2, dijkstra/traceback, capacity) calculates flows in a network.

Based on the results of impedance-obsolete-dijkstra calculations, the trace_back function results in the amount of flow for each link in the network.

The trace_back function requests four arguments:

  • F1: relation to the from node of each link;
  • F2: relation to the to node of each link;
  • dijkstra/traceback: the node to edge traceback item, a generated subitem by the impedance-obsolete-dijkstra
  • capacity: capacity indicator for each node.

applies to

  • attribute F1, F2 and dijkstra/traceback with uint32 value-type
  • attribute capacity with Numeric value type

conditions

The domain-unit of attributes F1 and F2 must match.

example

attribute<meter> dist (NodeSet) := dijkstra(dist, F1, F2, nr_DestNode);
attribute<nr_pers> flow (LinkSet) :=
   value(
      trace_back(
           F1
         , F2
         , dist/TraceBack
         , pcount(nr_OrgNode)
      )
      , nr_pers
   );
F1 F2 flow
8 7 0
1 4 2
16 15 0
2 3 1
5 4 1
6 7 2
9 10 1
12 11 1
14 15 0
18 20 1
19 17 1
3 0 0
4 11 1
7 1 2
10 3 1
11 13 0
13 17 0
15 10 0
20 21 0
17 20 1

domain Linkset, nr of rows = 19

nr_OrgNode
14
12
9
18
5

domain Origin, nr of rows = 5