Stopping turtles from having negative resources - netlogo

Question

My model creates a relationship between employees and citizens. Whereby the employees obtain office and then distribute to the employees:
globals [
office-space
]
breed [ offices office ]
breed [ service-desks service-desk ]
breed [ employees employee ]
breed [ citizens citizen ]
offices-own [ money ]
employees-own [ money ]
citizens-own [ money ]
to setup
clear-all
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 4 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]
;; set all employees randomly within the grey box
place-on-color-employees
;; set all citizens randomly outside of the grey box
place-on-color-citizens
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
ask employees [
set label money
]
ask citizens [
set label money
]
employee-movement-without-money
employee-take-money
employee-movement-with-money
citizens-movement
citizen-take-money
tick
end
to employee-movement-with-money
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 > 0 [
face target
fd 1
]
]
end
to employee-movement-without-money
ask employees [
let target patch 0 0
if ( money = 0 ) or ( money < 0 ) [
face target
fd 1
]
]
end
to citizens-movement
ask citizens [
ifelse [pcolor] of patch-ahead 1 = grey
[ rt random-float 360 ]
[ forward 1 ]
let target min-one-of service-desks [ distance myself ]
if money = 0 [
set heading (towards target )
]
]
end
to employee-take-money
ask employees [
if any? offices-here [
set money money + 1
set color green
;set label money
]
]
end
to citizen-take-money
ask citizens [
if any? employees in-radius 0.5 [
ask employees [
set money money - 1
]
]
set money money + 1
set color orange
]
end
When this model is run, the employees collect money and go to meet citizens, however, in the citizen-take-money procedure, I have not found a way to prevent the citizens from taking money from the employees so they don't have negative values. I tried adding the employee-movement-without-money to force the employees to turn move away from the citizens, but they just congregate on patch 0 0.
I also tried adjusting the citizens-take-money procedures by creating an if and arugment:
to citizen-take-money
ask citizens [
if (any? employees in-radius 0.5) and (employees money > 0) [
ask employees [
set money money - 1
]
]
set money money + 1
set color orange
]
end
But that didn't work either.

Answer 1

First piece of advice, build NetLogo models gradually. You need to make sure each piece works before adding the slightly more complicated behaviour. You should never have more than one thing wrong in a NetLogo model at the same time, very hard to debug.
Here, the basic problem appears to be that you are acting on all turtles instead of just the relevant turtle. Here is your supplementary code that tries to introduce a check:
to citizen-take-money
ask citizens [
if (any? employees in-radius 0.5) and (employees money > 0) [
ask employees [
set money money - 1
]
]
set money money + 1
set color orange
]
end
First, have a look at your check - conceptually, what are you testing with the second part employees money > 0. That doesn't actually look like valid NetLogo code to me, are you trying to ask if there are any employees with with money > 0?
Regardless, let's say it gets past that check, the next line is ask employees - at this point you are telling EVERY employee in the model to reduce their money.
What you need to do is just find the right employees and have those ones reduce their money. Something more like:
to citizen-take-money
ask citizens
[ let nearby employees in-radius 0.5 with [money > 0]
if any? nearby
[ ask nearby [ set money money - 1 ]
set money money + 1
set color orange
]
]
end
Also, this procedure is asking every citizen to do this and you have named it as if only one citizen is doing it. So think about which way you actually want the process to work.
Finally, what happens if you have several citizens close to several employees. Say 3 citizens reduce their money because they are close to the same employee - at the moment, the employee only increases their money by 1 and the remaining 2 disappears. This is an example of what I mean by build gradually and check it works before adding in the next thing. Perhaps you could have them just change colours if the condition is met before trying to add in the money transfers. That would help you spot that you had lots of people triggered at once.