How to get turtles to move to the target? - netlogo

Question

I'm stumped with an issue in my model. I have a model that looks to simulate an office environment, where there are two breeds: employees and citizens. The employees stay in the office, denoted by grey coloured patches, and the citizensstay in the outside world denoted by black colour patches.
In the middle of the world patch 0 0 there is an office, where employees go to pick up money. There are 4 service-desks where both employees and citizens are to meet for a transfer of money to occur. Here is the full code:
globals [ office-space ]
breed [ offices office ]
breed [ service-desks service-desk ]
breed [ employees employee ]
breed [ citizens citizen ]
offices-own [ money ]
employees-own [ money-held ]
citizens-own [ money-received ]
to setup
clear-all
create-offices 1
ask offices [
set shape "building institution"
set size 4
set color yellow
set money num-of-money ]
create-employees num-of-employees
ask employees [
set shape "person"
set size 1.5
set color blue
setxy random-xcor random-ycor ]
create-citizens num-of-citizens
ask citizens [
set shape "person"
set size 1.5
set color white
setxy random-xcor random-ycor ]
;; create four service desks
ask patch 0 8 [
sprout 1 [
set breed service-desks
set shape "building institution"
set color pink
set size 3 ]
]
ask patch 0 -8 [
sprout 1 [
set breed service-desks
set shape "building institution"
set color pink
set size 3 ]
]
ask patch -8 0 [
sprout 1 [
set breed service-desks
set shape "building institution"
set color pink
set size 3 ]
]
ask patch 8 0 [
sprout 1 [
set breed service-desks
set shape "building institution"
set color pink
set size 3 ]
]
;; create office space
set office-space patches with [ pxcor <= 8 and pxcor >= -8 and pycor <= 8 and pycor >= -8 ]
ask office-space [ set pcolor grey]
place-on-color-employees ;; sets all employees randomly within the grey square
place-on-color-citizens ;; sets citizens randomly outside of the grey box
reset-ticks
end
to place-on-color-employees
let _patches (patches with [pcolor = grey])
ask employees [
move-to one-of (_patches with [not any? turtles-here])
]
end
to place-on-color-citizens
let _patches (patches with [pcolor = black])
ask citizens [
move-to one-of (_patches with [not any? turtles-here])
]
end
to go
employee-movement
employee-take-money
citizen-movement
tick
end
to employee-movement
ask employees [
ifelse [pcolor] of patch-ahead 1 = black
[ rt random-float 360]
[ forward 1 ]
let target one-of citizens
if money-held > 0 [
set heading (towards target)
]
]
end
to citizen-movement
;; citizens walk only in the black patches, they do not go into the office area
ask citizens [
ifelse [pcolor] of patch-ahead 1 = grey
[ rt random-float 360]
[ forward 1 ]
;; if they have no money, then the citizens will walk to one of the service-desks
let target one-of service-desks
if money-received = 0 [
set heading (towards target )
]
]
end
to employee-take-money ;; asks employees to go to the main office and get money
ask employees [
if any? turtles-here with [ shape = "building institution" and color = yellow] [
set money-held money-held + 1
set color green ]
]
end
The issue I have is that within the employee-movement function, the employees will not move towards their targets. Whereas, the citizens will move to their targets. The code for both breeds is basically the same. The employees tend to congregate around the central patch, rather than moving to the targets.

Answer 1

Edited after receiving the full code:
The problem lies with how you define target as a local variable (let target one-of service-desks) each time you call the code. However, since there is more than one service-desk, nothing is forcing them to choose the same service-desk each time. This means that the employees, who are standing in the middle of the four service-desks, are basically taking a step in a random direction at each tick. The citizens on the other hand stand outside of the square on which the service-desks are located. Because of that, all of the service-desks are roughly in the same direction for them, so their general movement also goes in that direction.
I see two different options for working around this. The first one is to not use let target one-of service-desks but use let target min-one-of service-desks [distance myself]. This moves them to the closest service-desk rather than to a random service desk.
The other option would be to set target as a turtles-own variable, and not letting them choose a new one all the time.
Finally I streamlined your setup a little bit, reducing the amount of code you needed.
globals [
office-space
num-of-money
num-of-employees
num-of-citizens
]
breed [ offices office ]
breed [ service-desks service-desk ]
breed [ employees employee ]
breed [ citizens citizen ]
offices-own [ money ]
employees-own [ money-held ]
citizens-own [ money-received ]
to setup
clear-all
set num-of-money 100
set num-of-employees 5
set num-of-citizens 5
create-offices 1 [
set shape "building institution"
set size 4
set color yellow
set money num-of-money
]
create-employees num-of-employees [
set shape "person"
set size 1.5
set color blue
setxy random-xcor random-ycor
]
create-citizens num-of-citizens [
set shape "person"
set size 1.5
set color white
setxy random-xcor random-ycor
]
;; create four service desks
let service-desk-patches (patch-set patch 0 8 patch 8 0 patch 0 -8 patch -8 0)
ask service-desk-patches [
sprout-service-desks 1 [
set shape "building institution"
set color pink
set size 3
]
]
;; create office space
set office-space patches with [ pxcor <= 8 and pxcor >= -8 and pycor <= 8 and pycor >= -8 ]
ask office-space [ set pcolor grey]
place-on-color-employees ;; sets all employees randomly within the grey square
place-on-color-citizens ;; sets citizens randomly outside of the grey box
reset-ticks
end
to place-on-color-employees
let _patches (patches with [pcolor = grey])
ask employees [
move-to one-of (_patches with [not any? turtles-here])
]
end
to place-on-color-citizens
let _patches (patches with [pcolor = black])
ask citizens [
move-to one-of (_patches with [not any? turtles-here])
]
end
to go
employee-movement
employee-take-money
citizen-movement
tick
end
to employee-movement
ask employees [
ifelse [pcolor] of patch-ahead 1 = black
[ rt random-float 360]
[ forward 1 ]
let target min-one-of citizens [distance myself]
if money-held > 0 [
set heading (towards target)
]
]
end
to citizen-movement
;; citizens walk only in the black patches, they do not go into the office area
ask citizens [
ifelse [pcolor] of patch-ahead 1 = grey
[ rt random-float 360]
[ forward 1 ]
;; if they have no money, then the citizens will walk to one of the service-desks
let target min-one-of service-desks [distance myself]
if money-received = 0 [
set heading (towards target )
]
]
end
to employee-take-money ;; asks employees to go to the main office and get money
ask employees [
if any? offices-here [
set money-held money-held + 1
set color green ]
]
end