---hotelling-xvila.nlogo

NETLOGO

; add model procedures here

breeds [people firms]           
firms-own [ice-sold-today]
people-own [closest]
globals [firm1 firm2]

to setup
ca
ask random-n-of num-of-people patches  [sprout-people 1 [set color red set shape "person"]]
ask random-n-of 2 patches [sprout-firms 1 [set color blue set shape "truck"]]

set firm1 num-of-people
set firm2 (num-of-people + 1)
ask turtle firm1 [set color green]
end



to go
ask firms [set ice-sold-today 0]
if wander? [ask people [do-random-walk]]
ask people [
  ifelse distance-nowrap turtle firm1 < distance-nowrap turtle firm2
    [set closest firm1]
    [set closest firm2]
    ifelse move-if-close?
    [
      if distance-nowrap turtle closest < max-distance
      [set ice-sold-today-of turtle closest (ice-sold-today-of turtle closest + 1) ]
    ]
    [
      set ice-sold-today-of turtle closest (ice-sold-today-of turtle closest + 1)
    ]
           ] 
ifelse random? 
[
ifelse ice-sold-today-of turtle firm2 > ice-sold-today-of turtle firm1
 [ask turtle firm1 [ do-random-walk]]
 [ask turtle firm2 [ do-random-walk]]
]
[
ifelse ice-sold-today-of turtle firm2 > ice-sold-today-of turtle firm1
 [ask turtle firm1 [ set heading towards-nowrap turtle firm2 fd 1 ]]
 [ask turtle firm2 [ set heading towards-nowrap turtle firm1 fd 1 ]]
] 
update-plots
end

to do-random-walk
      rt random-float 360               ; set random heading 
      forward 1                         ; advance one step
end

to update-plots
set-current-plot "Ice Sold Today"
  set-current-plot-pen "Firm1"
  plot ice-sold-today-of turtle firm1
  set-current-plot-pen "Firm2"
  plot ice-sold-today-of turtle firm2
  
set-current-plot "Distance Traveled"
ifelse move-if-close?
[
set-current-plot-pen "Max"
plot max values-from people with [distance-nowrap turtle closest < max-distance ] [distance-nowrap turtle closest]
set-current-plot-pen "Mean"
plot mean values-from people with [distance-nowrap turtle closest < max-distance ][distance-nowrap turtle closest]
set-current-plot-pen "Min"
plot min values-from people with [distance-nowrap turtle closest < max-distance ][distance-nowrap turtle closest]
]
[
set-current-plot-pen "Max"
plot max values-from people [distance-nowrap turtle closest]
set-current-plot-pen "Mean"
plot mean values-from people [distance-nowrap turtle closest]
set-current-plot-pen "Min"
plot min values-from people [distance-nowrap turtle closest]
]
end
@#$#@#$#@
GRAPHICS-WINDOW
297
13
863
600
17
17
15.9
1
10
1
1
1
0

CC-WINDOW
5
614
872
709
Command Center

BUTTON
15
162
85
196
NIL
setup\n
NIL
1
T
OBSERVER
T
NIL

BUTTON
195
162
259
196
NIL
go
T
1
T
OBSERVER
T
NIL

BUTTON
100
162
187
196
Go once
go
NIL
1
T
OBSERVER
T
NIL

MONITOR
17
290
126
339
Firm 1 (Green)
ice-sold-today-of turtle (num-of-people)
0
1

MONITOR
131
291
245
340
Firm 2 (Blue)
ice-sold-today-of turtle (num-of-people + 1)
0
1

SLIDER
13
9
258
42
num-of-people
num-of-people
0
1000
1000
1
1
NIL

SWITCH
13
54
134
87
Wander?
Wander?
1
1
-1000

PLOT
18
349
247
470
Ice Sold Today
NIL
NIL
0.0
10.0
0.0
10.0
true
false
PENS
"Firm1" 1.0 0 -11352576 true
"Firm2" 1.0 0 -16776961 true

TEXTBOX
83
264
191
282
Ice-cream sold

SWITCH
138
55
260
88
random?
random?
1
1
-1000

PLOT
18
473
246
595
Distance Traveled
NIL
NIL
0.0
10.0
0.0
10.0
true
false
PENS
"default" 1.0 0 -65536 true
"Max" 1.0 0 -65536 true
"Mean" 1.0 0 -16776961 true
"Min" 1.0 0 -65413 true

SWITCH
13
102
151
135
move-if-close?
move-if-close?
0
1
-1000

MONITOR
15
208
83
257
x-Median
median values-from people [xcor]
3
1

MONITOR
91
208
155
257
y-Median
median values-from people [ycor]
3
1

MONITOR
225
209
289
258
y-Mean
mean values-from people [ycor]
3
1

MONITOR
158
208
223
257
x-Mean
mean values-from people [xcor]
3
1

SLIDER
157
101
284
134
max-distance
max-distance
0
48
10
1
1
NIL

@#$#@#$#@
WHAT IS IT?
-----------
This model represents a simple extension of the Hotelling spatial competition model by considering two dimensions.


HOW IT WORKS
------------
A "num-of-people" of consumers feel like having an ice-cream that is sold by any of the two firms (firm 1 and firm 2). At each moment, each consumer at a given position goes to the "closest" firm, buys an ice-cream, and returns to its original place.
Firms move around the world to attract new consumers. The rules are simple: If I get less consumers that my competitor, the I'll head towards its location.
There is the possibility that consumers wander around the world, which is controled by the "wander" switch in the interface


HOW TO USE IT
-------------
"Setup" will create a "num-of-people" consumers randomly spread around the world and two firms: firm 1 (green) and firm 2 (blue)

"Go" makes firms move around the world to gain consumers as described above

"Wander" makes consumers wander around



EXTENDING THE MODEL
-------------------
The rule for the movement of the firms is quite simple.
New rules should be tried.


CREDITS AND REFERENCES
----------------------
Copyright Xavier Vil