I am trying to move my citizens from one node (slocation) to another node (new-location) calculating the shortest path.
I could only calculate the distance from slocation to new-location using set total-expected-path [distance [slocation] of myself] of new-location.
However, I am pretty sure that the following line after to set total-expected-path are not correct. I got the following error: this code can't be run by a turtle, only a link error while node 35 running LINK-LENGTH
How can I define this distance calculate in the total-expected-path as the minimum between nodes using the link connection between nodes?
and after that, how can I move the turtles following this short path?
to go
set-timekeeper
ask citizens
[find-day-activities]
end
to set-timekeeper
tick
let counter ticks
if (counter = 2)
[set timekeeper 2]
end
to find-day-activities
if (timekeeper = 2)
[Do_7AM_9AM]
end
to Do_7AM_9AM
if (sex = 0 and age = 1 and employment = 0 and household-size = 0 [move-work]
end
to move-work
to move-work
set slocation min-one-of nodes [distance myself]
let new-location min-one-of nodes [distance one-of workbuildings]
let llocation one-of [link-neighbors with-min [link-length]] of new-location
move-to llocation
end
You may want to use the nw
extension to take advantage of the nw:turtles-on-path-to
or nw:turtles-on-weighted-path-to
primitives. With these extensions and variables:
extensions [nw]
breed [ nodes node ]
breed [ walkers walker ]
links-own [ weight ]
and this setup:
to setup-example
ca
let xs [ 10 -5 -5 -5 -5 2 ]
let ys [ 0 0 3 6 9 9 ]
( foreach xs ys [
[ x y ] ->
ask patch x y [
sprout-nodes 1 [
set shape "circle"
set color white
set size 2.5
]
]
])
let ind ( range 0 4 )
foreach ind [
i ->
let x item i xs
let y item i ys
let xn item ( i + 1 ) xs
let yn item ( i + 1 ) ys
ask nodes-on patch x y [
create-links-with nodes-on patch xn yn
]
]
while [ any? nodes with [ count my-links < 2 ] ] [
ask one-of nodes with [ count my-links < 2 ] [
let linkable min-one-of other nodes with [ count my-links < 2 ] [distance myself]
if linkable != nobody [
create-link-with linkable
]
]
]
ask nodes-on patch -5 0 [ set color green ]
ask nodes-on patch 2 9 [ set color red ]
end
This creates a loop network- pretend that the green is the start node and the red is the destination.
Now, using nw:turtles-on-path-to
you can identify the nodes in the path that gets to the destination by the fewest links:
to fewest-links
let start one-of nodes-on patch -5 0
let target one-of nodes-on patch 2 9
let path nobody
ask start [
set color green
set path but-first nw:turtles-on-path-to target
ask turtle-set path [ set color yellow ]
ask target [ set color red ]
]
end
Or, using link-length
as the weight
variable in nw:turtles-on-weighted-path-to
, you can get the shortest distance:
to shortest-distance
let start one-of nodes-on patch -5 0
let target one-of nodes-on patch 2 9
ask links [
set weight link-length
]
let path nobody
ask start [
set color green
set path but-first nw:turtles-on-weighted-path-to target weight
ask turtle-set path [ set color yellow ]
ask target [ set color red ]
]
end
To actually have your people move along a particular path, you can use a combination of the path identifying code above and foreach
. Example setup for that:
to setup
ca
create-nodes 10 [
set shape "circle"
set color white
set size 2.5
]
layout-circle nodes 10
while [ any? nodes with [ count my-links < 2 ] ] [
ask one-of nodes with [ count my-links < 2 ] [
let linkable min-one-of other nodes with [ count my-links < 2 ] [distance myself]
if linkable != nobody [
create-link-with linkable
]
]
]
ask one-of nodes [
set color green + 1
hatch-walkers 1 [
set color blue
set size 1.5
]
]
reset-ticks
end
And the movement itself:
to go
ask walkers [
; Randomly choose a target node to walk to
let target one-of nodes with [ color = white ]
if target != nobody [
; Remember the starting node
let current one-of nodes-here
; Define a path variable from the current node- take all but
; the first item (as first item is current node)
let path nobody
ask links [ set weight link-length ]
ask current [
set path but-first nw:turtles-on-weighted-path-to target weight
]
; Indicate the end node
ask last path [
set color red
set size 2.5
]
; Move along the path node-to-node
foreach path [
next-target ->
face next-target
move-to next-target
wait 0.25
ask next-target [
set color yellow
]
]
]
wait 1
; Reset
ask nodes [ set color white ]
ask one-of nodes-here [ set color green ]
]
end