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5.5-invasionPercolationWithTrapping.nlogo
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;; The MIT License (MIT)
;;
;; Copyright (c) 2011-24 David O'Sullivan and George Perry
;;
;; Permission is hereby granted, free of charge, to any person
;; obtaining a copy of this software and associated documentation
;; files (the "Software"), to deal in the Software without restriction,
;; including without limitation the rights to use, copy, modify, merge,
;; publish, distribute, sublicense, and/or sell copies of the Software,
;; and to permit persons to whom the Software is furnished to do so,
;; subject to the following conditions:
;;
;; The above copyright notice and this permission notice shall be included
;; in all copies or substantial portions of the Software.
;;
;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
;; OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
;; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
;; THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
;; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
;; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
;; DEALINGS IN THE SOFTWARE.
;;
extensions [ palette ]
globals [
last-invaded ;; the most recently invaded patch
next-to-invade ;; list of the patches subject to invasion next
max-x ;; max pxcor of invasion at each pycor
max-y ;; max pycor of invasion at each pxcor
min-y ;; min pycor of invasion at each pxcor
min-field
max-field
color-ramp-ends
]
patches-own [
invaded? ;; patch has been invaded
time-invaded ;; the time step when invasion occurred
p ;; U[0~1]
possible-successors ;; the 3 NSE neighbours
possible-predecessors ;; the 3 NSW neighbours
NX ;; the four diagonal neighbours
]
to setup
clear-all
random-field
let pal palette:scheme-colors "Sequential" "Blues" 3
set color-ramp-ends (list first pal last pal)
set min-field min [p] of patches
set max-field max [p] of patches
ask patches [
set invaded? false
set time-invaded -1
set possible-successors (patch-set (patch-at 1 0) (patch-at 0 1) (patch-at 0 -1))
set possible-predecessors (patch-set (patch-at -1 0) (patch-at 0 1) (patch-at 0 -1))
set NX (patch-set (patch-at 1 1) (patch-at -1 1) (patch-at -1 -1) (patch-at 1 -1))
]
repeat smoothing [ diffuse p 0.05 ]
;; tag and mark left, top and bottom edges as 'invaded'
ask patches with [pxcor = min-pxcor or pycor = min-pycor or pycor = max-pycor] [
set invaded? true
set pcolor grey
]
reset-ticks
;; max-x maintains for each pycor the max invaded pxcor in that row
set max-x (sentence max-pxcor n-values (max-pycor - 1) [min-pxcor] max-pxcor)
;; max-y and min-y maintain for each pxcor the region inside the invading cluster
set max-y n-values world-width [min-pycor]
set min-y n-values world-width [max-pycor]
set next-to-invade sort patches with [pxcor = 0 and pycor > min-pycor and pycor < max-pycor] with-min [p]
set last-invaded first next-to-invade
set next-to-invade but-first next-to-invade
ask last-invaded [set pcolor violet]
update-patch-states
end
to go
ask last-invaded [set pcolor white]
;; check for completion
if [pxcor] of last-invaded = max-pxcor [stop]
;; invade the next patch
set last-invaded first next-to-invade
;; remove the last-invaded
set next-to-invade but-first next-to-invade
update-patch-states
; check for traps?
if trapping? [
tag-traps patch-set [NX with [invaded?]] of last-invaded
]
tick
end
;; do book keeping on patch state variables
to update-patch-states
ask last-invaded [
set pcolor violet
set invaded? true
set time-invaded ticks
update-extent-lists pxcor pycor
]
ifelse stochastic? [
;; add any uninvaded possible successors of the last-invaded
set next-to-invade (patch-set next-to-invade ([possible-successors] of last-invaded) with [not member? self next-to-invade and not invaded?])
;; stochastic update
ask next-to-invade [ set p p + random-float-bnd (-1 * stochastic-shift) stochastic-shift ]
;; sort by the random-variable
set next-to-invade sort-by [ [patch1 patch2] -> [p] of patch1 < [p] of patch2 ] next-to-invade
]
[
; insert the new possible sites while maintaining sort order
ask last-invaded [
ask possible-successors with [not member? self next-to-invade and not invaded?] [
set next-to-invade insert-in-order next-to-invade self
]
]
]
end
;; reports a list with patch x inserted in list of patches lst
;; while maintaining it in sorted order by p value
;; ASSUMES that lst is already sorted by p values
to-report insert-in-order [lst x]
let posn length filter [ ptch -> [p] of ptch < [p] of x ] lst
report (sentence (sublist lst 0 posn) x (sublist lst posn (length lst)))
end
;; NOTE dependency on x,y coord 0 0 at origin...
to update-extent-lists [x y]
;; update the max invasion lists
if x > item y max-x [
set max-x replace-item y max-x x
]
if y = (max-pycor - 1) [
set max-y sentence (n-values (x + 1) [max-pycor]) (sublist max-y (x + 1) world-width)
]
if y > item x max-y [
set max-y replace-item x max-y y
]
if y = (min-pycor + 1) [
set min-y sentence (n-values (x + 1) [min-pycor]) (sublist min-y (x + 1) world-width)
]
if y < item x min-y [
set min-y replace-item x min-y y
]
end
;; tagging the traps associated with possible closure sites
to tag-traps [poss-closes]
if not any? poss-closes [stop]
let trap-seeds trap-seed-patches poss-closes
ask trap-seeds [
let escaped? false ;; trap is escaped to beyond invasion
let clean-up nobody ;; all patches considered by the search, which have to be cleaned up
let this-trap patch-set self
while [any? this-trap and not escaped?] [
set clean-up (patch-set clean-up this-trap)
let next-this-trap nobody ;; a list of the next set of patches in the same trap
ask this-trap [
set invaded? true
]
ask this-trap [
let N4 neighbors4 with [not invaded?]
ask N4 [
set escaped? escaped? or (pxcor > item pycor max-x)
or (pycor > item pxcor max-y)
or (pycor < item pxcor min-y)
]
set next-this-trap (patch-set N4 next-this-trap)
]
set this-trap next-this-trap
]
ifelse escaped? [ ;; then undo the tagging
ask clean-up [ set invaded? false ]
]
[ ;; else colour grey and remove from the next-to-invade list
ask clean-up [ set pcolor cyan - 2 ]
set next-to-invade filter [ ptch -> [not invaded?] of ptch ] next-to-invade
]
]
end
;; reports seed locations for possible traps arising from
;; the current last-invaded and the supplied list of neighbouring
;; invaded sites
to-report trap-seed-patches [sites]
let trap-seeds nobody ;; initialise the seed sites to empty
ask last-invaded [
;; all possibles are the uninvaded N4 of the last-invaded site
let immed-trap-seeds neighbors4 with [not invaded?]
;; then for each closure site...
ask sites [
;; intersect N4 with the uninvaded N4
let new-trap-seeds neighbors4 with [member? self immed-trap-seeds]
;; and append to the set of seed sites
set trap-seeds (patch-set trap-seeds new-trap-seeds)
]
]
report trap-seeds
end
;; Colour each patch by its p (underlying random field) value
to colour-field
ask patches with [not invaded?] [
set pcolor palette:scale-gradient color-ramp-ends p 0 1
]
end
to colour-by-time
ask patches with [time-invaded > -1] [
set pcolor palette:scale-scheme "Sequential" "YlOrRd" 9 time-invaded ticks -1
]
end
to random-field
ask patches [set p random-float 1]
end
to-report random-float-bnd [a b]
report random-float (b - a) + a
end
@#$#@#$#@
GRAPHICS-WINDOW
79
10
727
339
-1
-1
1.0
1
10
1
1
1
0
0
0
1
0
639
0
319
0
0
1
ticks
100.0
BUTTON
8
10
71
43
NIL
setup
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
BUTTON
8
47
71
80
step
go
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
BUTTON
8
84
71
117
NIL
go
T
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
BUTTON
9
121
73
154
go-10
repeat 10 [go]
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
SLIDER
24
211
57
361
smoothing
smoothing
0
100
0.0
1
1
NIL
VERTICAL
BUTTON
8
158
72
191
go-100
repeat 100 [go]
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
MONITOR
754
317
844
362
invasion-front
length next-to-invade
0
1
11
SWITCH
756
235
870
268
trapping?
trapping?
0
1
-1000
TEXTBOX
88
347
727
377
Set view updates to continuous or if it is set to 'on ticks' then make sure the speed slider is set towards the faster end of the range. Otherwise, this model will run very slowly.
12
0.0
1
BUTTON
755
191
876
224
colour-by-time
colour-by-time
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
SWITCH
758
56
875
89
stochastic?
stochastic?
1
1
-1000
SLIDER
758
17
891
50
stochastic-shift
stochastic-shift
0
0.05
0.005
0.0025
1
NIL
HORIZONTAL
BUTTON
757
155
875
188
NIL
colour-field
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
TEXTBOX
761
90
911
145
Note: this GREATLY slows the process, esp. if there is no trapping. Go and get a coffee.
11
15.0
1
TEXTBOX
758
276
908
306
Will run a lot slower with trapping OFF.
11
15.0
1
@#$#@#$#@
## WHAT IS IT?
This model simulates _invasion percolation_ as discussed in Chapter 5 of
+ O'Sullivan D and Perry GLW 2013 _Spatial Simulation: Exploring Pattern and Process_. Wiley, Chichester, England.
You should consult that book for more information and details of the model.
## INVASION PERCOLATION
Invasion percolation (IP) is a much less well known form of percolation than site percolation as portrayed in previous Chapter 5 models.
The process is as follows:
+ a grid is initialized with random values
+ the location with the lowest value on the left hand edge of the space is designated the *invasion front*
+ non-invaded locations adjacent to the front to the right or above and below cells in the front are invasible, and the site with the lowest value is invaded, and added to the front
The last step is repeated until the invasion front reaches the right hand edge of the space.
One wrinkle is *trapping* when a set of grid cells are cut off from a path to the right hand edge. If trapped locations are not identified then a model run can take a very long time while trapped locations are invaded, with no prospect of the invasion front reaching the right hand edge from such starting points. This is controlled in the model with the **trapping?** switch. It is recommended this switch generally be set **on**.
It may help to understand the process if you change the world dimensions to 160 wide by 80 high and the patch size to 4, then run the model with the update set to 'On ticks'. If necessary slow it down. You might also stop it occasionally and enter
(foreach next-to-invade range length next-to-invade [[x i] -> ask x [set plabel i]])
This will label all the patches in the 'queue' to be invaded next (from lowest value to highest). You will notice that the lower ones tend to be close to the current tip of the invasion (in red). This is because other locations in the queue have been 'paths not taken' previously and hence are likely to be in the higher range of the random field values. This dynamic is what gives the process its characteristic multiple branching structure.
## THINGS TO NOTICE
The complicated part of this model is associated with detecting traps. The basic algorithm above is operated by maintaing a queue `next-to-invade`. This is a list of patches next to already invaded patches (strictly north, south or east of invaded patches), that is kept ordered by the randomly generated `p` values assigned during model setup. Maintenance of the queue order is managed by the `insert-in-order` procedure. By this means the basic operation is
while not at right edge [
invade first patch in next-to-invade-list
add newly identified N/S/E neighbours of invasion to next-to-invade
]
The complication is trap detection. Honestly, I have a hard time figuring it all out. **YOU SHOULD ALWAYS DOCUMENT CODE WHEN YOU ARE WRITING IT!** But here is my thinking...
**COMING SOON...**
## HOW TO CITE
If you mention this model in a publication, please include these citations for the model itself and for NetLogo
+ O'Sullivan D and Perry GLW 2013 _Spatial Simulation: Exploring Pattern and Process_. Wiley, Chichester, England.
+ Wilensky U 1999 NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
## COPYRIGHT AND LICENSE
The MIT License (MIT)
Copyright © 2011-24 David O'Sullivan and George Perry
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
@#$#@#$#@
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@#$#@#$#@
NetLogo 6.4.0
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@
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@#$#@#$#@
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@#$#@#$#@
0
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