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Ian
Ian

Reputation: 3

How to find the next turtle on a network weighted path to destination in NetLogo?

I'm running a traffic interaction simulator with an imported shapefile that generates a road network. Nodes and links between nodes along this network are created that agents travel between. This has all been ironed out with the network extension, nw:turtles-on-path-to command, but to incorporate speed limits I'm trying to implement weighted path-finding. So links between nodes also have a speedLimit weight variable.

This is the current code which works - what I'm trying to do is change the 'nw:turtles-on-path-to [destination]' into 'nw:turtles-on-weighted-path-to [destination speedLimit]'. However, the 'of' nesting is proving problematic when adding the weight variable and throws up errors seemingly no matter how I try and add it in. 

to set-location
  set current-location min-one-of nodes [distance myself]
end

to set-destination
  let test current-location
  nested-set-destination
  while [destination = test] [nested-set-destination]
  set next-node item 1 [nw:turtles-on-path-to [destination] of myself] of current-location
  face next-node
end

to nested-set-destination
  set destination one-of [ nodes with [is-number? [ nw:distance-to myself ] of myself] ] of current-location
end

to move
  let test-location min-one-of nodes [distance myself]
  if (any? nodes with [distance myself < 1]) and (test-location != current-location) [
    set current-location min-one-of nodes [distance myself]
    ifelse current-location = destination [
      set-destination
    ]
    [
      set next-node item 1 [nw:turtles-on-path-to [destination] of myself] of current-location
      face next-node
    ]
  ]
  fd speed
end

Throws up 'Error - expected closing bracket' and highlights speedLimit if I make the described changes. If I instead enclose it like so...

set next-node item 1 [[nw:turtles-on-weighted-path-to destination speedLimit] of myself] of current-location

... this can make it past code check, but once the function is called returns "ITEM expected input to be a string or list but got the TRUE/FALSE false instead."

Upvotes: 0

Views: 115

Answers (1)

JenB
JenB

Reputation: 17678

Sometimes the easiest way to deal with awkward syntax is to avoid it entirely, and that also makes for more readable code. In this case, I would create a temporary variable for the destination and use that. So instead of doing it all in one command, something like:

let target [destination] of myself
set next-node item 1 nw:turtles-on-weighted-path-to target speedLimit

But if you definitely want it in one line, brackets could help:

set next-node item 1 nw:turtles-on-weighted-path-to ([destination] of myself) speedLimit

Upvotes: 1

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