;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; variable declarations ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;

globals
[
  clock            ;; the number of elapsed ticks
  sum-right-turns  ;; the sum of turtles that turned right for the entire run
  sum-left-turns   ;; the sum of turtles that turned left for the entire run
]

;;;;;;;;;;;;;;;;;;;;;;
;; setup procedures ;;
;;;;;;;;;;;;;;;;;;;;;;

;; this sets up the patches and creates turtles so that we can run the model
to setup
  ca
  ask patches
    [ init-patch ]
  setup-turtles
  init-vars
  setup-plot
end

;; set up the patch color 
to init-patch  ;; patch procedure
  ifelse pxcor = 0
    [ set pcolor 6 ]
    [ set pcolor 8 ]
end

;; determines the number of turtles and their color
;; if turtle-trails? is on, the turtles' pens should be down,
;; otherwise they should be up
to setup-turtles
  cct number-of-turtles
  [
    set color black
    ifelse turtle-trails?
      [ pd ]  ;; have the turtles put down their pens
      [ pu ]  ;; have the turtles pick up their pens
    setxy 0 ( - screen-edge-x )
    set heading 0
  ]
end

;; counts the number of right and left turns and paces of the turtles
to init-vars
  set clock 0
  set sum-right-turns 0
  set sum-left-turns 0
end

;; setup the plot which measures the turtles' movement during the run
to setup-plot
  set-current-plot "Number of Steps in Each Direction"
  set-plot-y-range 0 (count turtles * .75)
  set-plot-x-range 0 (screen-size-y)
  draw-plot 0 0
end

;;;;;;;;;;;;;;;;;;;;;;;;
;; runtime procedures ;;
;;;;;;;;;;;;;;;;;;;;;;;;

;; have the turtles randomly pick either right or left and
;; have them move in that direction
;; if one turtle cannot move, then stop
to go
  locals
  [
    num-turtles-right  ;; the number of turtles turning right currently
    num-turtles-left   ;; the number of turtles turning left currently
  ]

  set num-turtles-right 0
  set num-turtles-left 0

  ;; if one turtles cannot move without wrapping around the screen, then stop
  if any? turtles with
       [(ycor > (screen-edge-y - number-of-steps)) or 
        (xcor > (screen-edge-x - number-of-steps)) or 
        (xcor < (( - screen-edge-x ) + number-of-steps))]
    [ stop ]
  
  set clock clock + 1
 
  ask turtles
  [
    ifelse ((random 2) = 0)
    [
      go-left
      set num-turtles-left (num-turtles-left + 1)
    ]
    [
      go-right
      set num-turtles-right (num-turtles-right + 1)
    ]
    
    ;; set the color of the turtles to give a rough idea of how many turtles 
    ;; are at each location -- the lighter the color, the greater the number
    ;; of turtles
    set color scale-color blue (count turtles-here) (number-of-turtles / 5) 0
  ]

  ;; do plotting
  draw-plot num-turtles-right num-turtles-left

  ;; update the sums of right and left turns
  set sum-right-turns (sum-right-turns + num-turtles-right)
  set sum-left-turns (sum-left-turns + num-turtles-left)
end

;; turn left and go one-pace
to go-left  ;; turtle procedure
  lt 90
  one-pace
end

;; go forward number-of-steps, turn upwards and go forward number-of-steps
to one-pace  ;; turtle procedure
  fd number-of-steps
  set heading 0
  fd number-of-steps
end

;; turn right and go one-pace
to go-right  ;; turtle procedure
  rt 90
  one-pace
end

;; update the plot
to draw-plot [ num-right num-left ]
  set-current-plot-pen "Turned Right"
  plot num-right
  set-current-plot-pen "Turned Left"
  plot num-left
end


; *** NetLogo Model Copyright Notice ***
;
; This model was created as part of the project: CONNECTED MATHEMATICS:
; MAKING SENSE OF COMPLEX PHENOMENA THROUGH BUILDING OBJECT-BASED PARALLEL
; MODELS (OBPML).  The project gratefully acknowledges the support of the
; National Science Foundation (Applications of Advanced Technologies
; Program) -- grant numbers RED #9552950 and REC #9632612.
;
; Copyright 1998 by Uri Wilensky. All rights reserved.
;
; Permission to use, modify or redistribute this model is hereby granted,
; provided that both of the following requirements are followed:
; a) this copyright notice is included.
; b) this model will not be redistributed for profit without permission
;    from Uri Wilensky.
; Contact Uri Wilensky for appropriate licenses for redistribution for
; profit.
;
; This model was converted to NetLogo as part of the project:
; PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN
; CLASSROOMS.  The project gratefully acknowledges the support of the
; National Science Foundation (REPP program) -- grant number REC #9814682.
; Converted from StarLogoT to NetLogo, 2002.  Updated 2002.
;
; To refer to this model in academic publications, please use:
; Wilensky, U. (1998).  NetLogo Random Walk Left Right model.
; http://ccl.northwestern.edu/netlogo/models/RandomWalkLeftRight.
; Center for Connected Learning and Computer-Based Modeling,
; Northwestern University, Evanston, IL.
;
; In other publications, please use:
; Copyright 1998 by Uri Wilensky.  All rights reserved.  See
; http://ccl.northwestern.edu/netlogo/models/RandomWalkLeftRight
; for terms of use.
;
; *** End of NetLogo Model Copyright Notice ***
@#$#@#$#@
GRAPHICS-WINDOW
415
10
740
356
17
17
9.0
1
10
1
1
1

CC-WINDOW
415
357
730
477
Command Center

MONITOR
13
141
134
190
Sum of Left Turns
sum-left-turns
3
1

MONITOR
13
195
134
244
Sum of Right Turns
sum-right-turns
3
1

PLOT
3
250
407
480
Number of Steps in Each Direction
Time-Ticks
Number of Steps
0.0
35.0
0.0
187.5
true
true
PENS
"Turned Right" 1.0 0 -65536 true
"Turned Left" 1.0 0 -16776961 true

SWITCH
171
95
312
128
turtle-trails?
turtle-trails?
0
1
-1000

SLIDER
146
179
318
212
number-of-steps
number-of-steps
1
10
2
1
1
NIL

SLIDER
146
139
318
172
number-of-turtles
number-of-turtles
1
500
250
1
1
NIL

MONITOR
13
86
70
135
Clock
Clock
0
1

BUTTON
217
42
298
78
Go
go
T
1
T
OBSERVER
T

BUTTON
109
42
190
78
Go Once
go
NIL
1
T
OBSERVER
T

BUTTON
14
42
86
78
Setup
setup
NIL
1
T
OBSERVER
T

@#$#@#$#@
WHAT IS IT?
-----------
This is a model to simulate a random walk.  In this simulation, all turtles walk to the left and forward or they walk to the right and forward.  The turtles randomly choose between either direction each time they move.

The path traced out by the turtles moving in this pattern is called a lattice.

As the simulation continues, one can expect the turtles to become more spread out.  Observe the kinds of patterns that develop as the turtles move.

Shading of turtles is representative of how many turtles share that location. Dark shades imply more turtles.  Light shades imply fewer turtles.

For purposes of this simulation, "forward" will mean moving toward the top of the screen, "left" will mean moving toward the left edge of the screen, and "right" will mean moving toward the right edge of the screen.


HOW TO USE IT
-------------
Use the NUMBER-OF-TURTLES slider to select how many turtles will participate in the random walk.

Use the NUMBER-OF-STEPS slider to decide how many steps a turtle will take on each turn.

How steps are implemented:
- If NUMBER-OF-STEPS is set to 1 and a turtle is going left, it will go left one step and then go forward one step. (Imagine a turtle walking along the bottom and left edge of a 1 x 1 square.)
- If NUMBER-OF-STEPS is set to 4 and a turtle is going left, it will go left four steps and then go forward four steps. (Imagine a turtle walking along the bottom and left edge of a 4 x 4 square.)
- Each of the above movements would be considered a single "pace."

The CLOCK monitor displays how many paces the turtles have taken.

Use the TURTLE-TRAILS? switch to have the turtles put their pens down to trace their paths and show the part of the lattice they are covering.  This switch must be set before the SETUP button is pressed.

All sliders except NUMBER-OF-TURTLES may be changed during a simulation.

Press the SETUP when all of the above selections have been made. This will create the selected number of turtles at the bottom center of the screen.

Press GO ONCE button to make the turtles move one pace.

Press the GO button to make the turtles move until one of the turtles cannot complete its number of steps.  When one turtle reaches this point, all the other turtles will stop even if they can complete the step.

To stop the simulation while it is running, press the GO button again.

The gray bar in the middle of the screen is at xcor = 0.  This is where all the turtles start.


THINGS TO TRY
-------------
Try to answer the questions below before running the simulations.  

Record your predictions.  Compare your predicted results with the actual results.
- What reasoning led you to correct predictions?
- What assumptions that you made need to be revised?

Try different numbers of turtles while keeping all other slider values the same.

Try different numbers of steps while keeping all other slider values the same.
   

THINGS TO NOTICE
----------------  
Think about how you would define an "average" turtle and an "average" walk.

Where would you expect an average turtle to end up at the end of the simulation?  Why?

How many paces would you expect there to be in an average walk?  Why?

What kinds of calculations or measurements would you use in trying to answer these questions?

How do your answers to the above questions compare to the average of the x coordinates of all the turtles?


EXTENDING THE MODEL
-------------------
As the model stands, it plots two lines (right and left) over time. Another way to look at this simulation is to plot the distribution of turtles.  Create a histogram to show this type of data.

The turtles will stop if they come up to an obstacle (cannot move forward or to the right/left), give the turtles the ability to think ahead and choose a different step/direction.

Give the turtles the ability to walk backwards.

Create a three dimensional lattice.

    
RELATED MODELS
--------------
Random Walk 360, Galton Box, Binomial Rabbits


CREDITS AND REFERENCES
----------------------
To refer to this model in academic publications, please use: Wilensky, U. (1998).  NetLogo Random Walk Left Right model. http://ccl.northwestern.edu/netlogo/models/RandomWalkLeftRight. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

In other publications, please use: Copyright 1998 by Uri Wilensky.  All rights reserved.  See http://ccl.northwestern.edu/netlogo/models/RandomWalkLeftRight for terms of use.
@#$#@#$#@
default
true
0
Polygon -7566196 true true 150 5 40 250 150 205 260 250

ant
true
0
Polygon -7566196 true true 136 61 129 46 144 30 119 45 124 60 114 82 97 37 132 10 93 36 111 84 127 105 172 105 189 84 208 35 171 11 202 35 204 37 186 82 177 60 180 44 159 32 170 44 165 60
Polygon -7566196 true true 150 95 135 103 139 117 125 149 137 180 135 196 150 204 166 195 161 180 174 150 158 116 164 102
Polygon -7566196 true true 149 186 128 197 114 232 134 270 149 282 166 270 185 232 171 195 149 186 149 186
Polygon -7566196 true true 225 66 230 107 159 122 161 127 234 111 236 106
Polygon -7566196 true true 78 58 99 116 139 123 137 128 95 119
Polygon -7566196 true true 48 103 90 147 129 147 130 151 86 151
Polygon -7566196 true true 65 224 92 171 134 160 135 164 95 175
Polygon -7566196 true true 235 222 210 170 163 162 161 166 208 174
Polygon -7566196 true true 249 107 211 147 168 147 168 150 213 150

arrow
true
0
Polygon -7566196 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150

bee
true
0
Polygon -256 true false 152 149 77 163 67 195 67 211 74 234 85 252 100 264 116 276 134 286 151 300 167 285 182 278 206 260 220 242 226 218 226 195 222 166
Polygon -16777216 true false 150 149 128 151 114 151 98 145 80 122 80 103 81 83 95 67 117 58 141 54 151 53 177 55 195 66 207 82 211 94 211 116 204 139 189 149 171 152
Polygon -7566196 true true 151 54 119 59 96 60 81 50 78 39 87 25 103 18 115 23 121 13 150 1 180 14 189 23 197 17 210 19 222 30 222 44 212 57 192 58
Polygon -16777216 true false 70 185 74 171 223 172 224 186
Polygon -16777216 true false 67 211 71 226 224 226 225 211 67 211
Polygon -16777216 true false 91 257 106 269 195 269 211 255
Line -1 false 144 100 70 87
Line -1 false 70 87 45 87
Line -1 false 45 86 26 97
Line -1 false 26 96 22 115
Line -1 false 22 115 25 130
Line -1 false 26 131 37 141
Line -1 false 37 141 55 144
Line -1 false 55 143 143 101
Line -1 false 141 100 227 138
Line -1 false 227 138 241 137
Line -1 false 241 137 249 129
Line -1 false 249 129 254 110
Line -1 false 253 108 248 97
Line -1 false 249 95 235 82
Line -1 false 235 82 144 100

bird1
false
0
Polygon -7566196 true true 2 6 2 39 270 298 297 298 299 271 187 160 279 75 276 22 100 67 31 0

bird2
false
0
Polygon -7566196 true true 2 4 33 4 298 270 298 298 272 298 155 184 117 289 61 295 61 105 0 43

boat1
false
0
Polygon -1 true false 63 162 90 207 223 207 290 162
Rectangle -6524078 true false 150 32 157 162
Polygon -16776961 true false 150 34 131 49 145 47 147 48 149 49
Polygon -7566196 true true 158 33 230 157 182 150 169 151 157 156
Polygon -7566196 true true 149 55 88 143 103 139 111 136 117 139 126 145 130 147 139 147 146 146 149 55

boat2
false
0
Polygon -1 true false 63 162 90 207 223 207 290 162
Rectangle -6524078 true false 150 32 157 162
Polygon -16776961 true false 150 34 131 49 145 47 147 48 149 49
Polygon -7566196 true true 157 54 175 79 174 96 185 102 178 112 194 124 196 131 190 139 192 146 211 151 216 154 157 154
Polygon -7566196 true true 150 74 146 91 139 99 143 114 141 123 137 126 131 129 132 139 142 136 126 142 119 147 148 147

boat3
false
0
Polygon -1 true false 63 162 90 207 223 207 290 162
Rectangle -6524078 true false 150 32 157 162
Polygon -16776961 true false 150 34 131 49 145 47 147 48 149 49
Polygon -7566196 true true 158 37 172 45 188 59 202 79 217 109 220 130 218 147 204 156 158 156 161 142 170 123 170 102 169 88 165 62
Polygon -7566196 true true 149 66 142 78 139 96 141 111 146 139 148 147 110 147 113 131 118 106 126 71

box
true
0
Polygon -7566196 true true 45 255 255 255 255 45 45 45

butterfly1
true
0
Polygon -16777216 true false 151 76 138 91 138 284 150 296 162 286 162 91
Polygon -7566196 true true 164 106 184 79 205 61 236 48 259 53 279 86 287 119 289 158 278 177 256 182 164 181
Polygon -7566196 true true 136 110 119 82 110 71 85 61 59 48 36 56 17 88 6 115 2 147 15 178 134 178
Polygon -7566196 true true 46 181 28 227 50 255 77 273 112 283 135 274 135 180
Polygon -7566196 true true 165 185 254 184 272 224 255 251 236 267 191 283 164 276
Line -7566196 true 167 47 159 82
Line -7566196 true 136 47 145 81
Circle -7566196 true true 165 45 8
Circle -7566196 true true 134 45 6
Circle -7566196 true true 133 44 7
Circle -7566196 true true 133 43 8

circle
false
0
Circle -7566196 true true 34 34 230

person
false
0
Circle -7566196 true true 155 20 63
Rectangle -7566196 true true 158 79 217 164
Polygon -7566196 true true 158 81 110 129 131 143 158 109 165 110
Polygon -7566196 true true 216 83 267 123 248 143 215 107
Polygon -7566196 true true 167 163 145 234 183 234 183 163
Polygon -7566196 true true 195 163 195 233 227 233 206 159

spacecraft
true
0
Polygon -7566196 true true 150 0 180 135 255 255 225 240 150 180 75 240 45 255 120 135

thin-arrow
true
0
Polygon -7566196 true true 150 0 0 150 120 150 120 293 180 293 180 150 300 150

truck-down
false
0
Polygon -7566196 true true 225 30 225 270 120 270 105 210 60 180 45 30 105 60 105 30
Polygon -8716033 true false 195 75 195 120 240 120 240 75
Polygon -8716033 true false 195 225 195 180 240 180 240 225

truck-left
false
0
Polygon -7566196 true true 120 135 225 135 225 210 75 210 75 165 105 165
Polygon -8716033 true false 90 210 105 225 120 210
Polygon -8716033 true false 180 210 195 225 210 210

truck-right
false
0
Polygon -7566196 true true 180 135 75 135 75 210 225 210 225 165 195 165
Polygon -8716033 true false 210 210 195 225 180 210
Polygon -8716033 true false 120 210 105 225 90 210

turtle
true
0
Polygon -7566196 true true 138 75 162 75 165 105 225 105 225 142 195 135 195 187 225 195 225 225 195 217 195 202 105 202 105 217 75 225 75 195 105 187 105 135 75 142 75 105 135 105

wolf-left
false
3
Polygon -6524078 true true 117 97 91 74 66 74 60 85 36 85 38 92 44 97 62 97 81 117 84 134 92 147 109 152 136 144 174 144 174 103 143 103 134 97
Polygon -6524078 true true 87 80 79 55 76 79
Polygon -6524078 true true 81 75 70 58 73 82
Polygon -6524078 true true 99 131 76 152 76 163 96 182 104 182 109 173 102 167 99 173 87 159 104 140
Polygon -6524078 true true 107 138 107 186 98 190 99 196 112 196 115 190
Polygon -6524078 true true 116 140 114 189 105 137
Rectangle -6524078 true true 109 150 114 192
Rectangle -6524078 true true 111 143 116 191
Polygon -6524078 true true 168 106 184 98 205 98 218 115 218 137 186 164 196 176 195 194 178 195 178 183 188 183 169 164 173 144
Polygon -6524078 true true 207 140 200 163 206 175 207 192 193 189 192 177 198 176 185 150
Polygon -6524078 true true 214 134 203 168 192 148
Polygon -6524078 true true 204 151 203 176 193 148
Polygon -6524078 true true 207 103 221 98 236 101 243 115 243 128 256 142 239 143 233 133 225 115 214 114

wolf-right
false
3
Polygon -6524078 true true 170 127 200 93 231 93 237 103 262 103 261 113 253 119 231 119 215 143 213 160 208 173 189 187 169 190 154 190 126 180 106 171 72 171 73 126 122 126 144 123 159 123
Polygon -6524078 true true 201 99 214 69 215 99
Polygon -6524078 true true 207 98 223 71 220 101
Polygon -6524078 true true 184 172 189 234 203 238 203 246 187 247 180 239 171 180
Polygon -6524078 true true 197 174 204 220 218 224 219 234 201 232 195 225 179 179
Polygon -6524078 true true 78 167 95 187 95 208 79 220 92 234 98 235 100 249 81 246 76 241 61 212 65 195 52 170 45 150 44 128 55 121 69 121 81 135
Polygon -6524078 true true 48 143 58 141
Polygon -6524078 true true 46 136 68 137
Polygon -6524078 true true 45 129 35 142 37 159 53 192 47 210 62 238 80 237
Line -16777216 false 74 237 59 213
Line -16777216 false 59 213 59 212
Line -16777216 false 58 211 67 192
Polygon -6524078 true true 38 138 66 149
Polygon -6524078 true true 46 128 33 120 21 118 11 123 3 138 5 160 13 178 9 192 0 199 20 196 25 179 24 161 25 148 45 140
Polygon -6524078 true true 67 122 96 126 63 144

@#$#@#$#@
NetLogo 2.0beta5
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@