Wurzer, Lorenz, Popov: „NetLogo Workshop (Part 1)“, in eCAADe 2012 Prague, Slide 1 „Netlogo First Steps (Artif. Societies) “, in Social Simulation Conference.

Wurzer, Lorenz, Popov: „NetLogo Workshop (Part 1)“, in eCAADe 2012 Prague, Slide 1 „Netlogo First Steps (Artif. Societies) “, in Social Simulation Conference 2014, Barcelona, Slide 1

PLEASE HAVE NETLOGO INSTALLED

- it‘s open source - available for windows, mac and linux- download:

GOOGLE „NETLOGO“ - FIRST LINK – DOWNLOAD

- DON‘T FORGET TO INSTALL AFTER DOWNLOADING (TAKES 3 MINUTES)

NETLOGO FIRST STEPS(ARTIFICIAL SOCIETIES)

Gabriel WurzerVienna University of [email protected]

„Netlogo First Steps (Artif. Societies) “, in Social Simulation Conference 2014, Barcelona, Slide 3

YOU GET WHAT YOU SEE HERE

place user interface elements here

see the world

here

type code here


THE NETLOGO WORLD

..is a 3D grid, of which

we show only a 2D slice:

• origin in the middle

• X+ goes right• Y+ goes into

screen• Z+ goes up (not

shown, assuming that z=0)


THE NETLOGO WORLD

• grid consists of patches (grid cells)

• each patch is identified by the coordinate at its center,

e.g. patch 0 0 0 at origin


THE NETLOGO WORLD

• grid consists of patches (grid cells)

• each patch is identified by the coordinate at its center,

or patch 1 1 0 as shown here


AGENTS („TURTLES“)

• movable entities within NetLogo

heading

xcorycorzcor

- 0..360 degrees- 0 is north, 90 east, etc.

- in grid coordinates- e.g. 0, 0, 0

pitch

- 0...360 degrees- 0 is level, 90 up, 270

downroll

- 0...360 degrees- rotation of wingtip- 0 is parallel to XY plane



• movable entities within NetLogo

heading

xcorycorzcor

- 0..360 degrees- 0 is north, 90 east, etc.

- in grid coordinates- e.g. 0, 0, 0 or 0.5, 0.5, 0

pitch

- 0...360 degrees- 0 is level, 90 up, 270

downroll

- 0...360 degrees- rotation of wingtip- 0 is parallel to XY plane


• can change their appearence


shape

color

size

- e.g. „default“




shape

color

size

- e.g. „default“ or „person“




shape

color

size


- relative to patch size- 1 is the default




shape

color

size


- relative to patch size- 1 is the default- but can be 2 as well




shape

color

size



- can be specified using words,- e.g. RED, GREEN, BLUE




shape

color

size



- can be specified using words,- e.g. RED, GREEN, BLUE or MAGENTA




hidden?

- default: false




hidden?

- default: false- can set to true

as well


• have a pen glued to their belly


pen-mode

- default: „up“, can also be „down“

pen-size




pen-mode

- default: „up“, can also be „down“- when the turtle moves with pen down, it will leave trails- trail colors corresponds

to the turtle‘s color

pen-size




pen-mode

- default: „up“, can also be „down“- when the turtle moves with pen down, it will leave trails- trail colors corresponds

to the turtle‘s color

pen-size

- may also influence the thickness of the trail


change theseto make anagent move



change theseto make anagent move


- special property containing the ID

of the turtle (e.g. turtle 0)


cannot move

PATCHES

- are addressed by their center, e.g. patch 0 0 0


HANDS ON

• start NetLogo 3D • type into the

observer

create-turtles 1


SEE THE RESULT


RIGHT MOUSE-CLICK THE TURTLE


CHOOSE TURTLE 0 > INSPECT TURTLE 0

…turtle 0inspect patch 0 0 -16inspect patch 0 0 -15inspect patch 0 0 -15

inspect turtle 0watch turtle 0follow turtle 0ride turtle 0


HERE YOU GO, NOW…

• see the properties we talked about here

• change them & see the 3D view:pen-mode „down“xcor 10ycor 10zcor 10hidden? true


NUMBERS

• are entered as-is• you cannot change „who“• colors are numbers, too

(see Tools>Color Swatches)

color name number

RED 15

BLACK 0

WHITE 9.9


STRINGS

• enter with quotation marks• pen-mode: „up“ or „down“• shapes(see Tools>Turtle Shapes

Editor) are for example:

shape name looks like

„default“

„person“

„arrow“


BOOLEANS

• enter either true or false


AGAIN, RIGHT-CLICK


CHOOSE INSPECT PATCH 0 0 -16

• SEE THAT YOU CAN CHANGE THE PROPERTIES THERE THE SAME WAY

…turtle 0inspect patch 0 0 -16inspect patch 0 0 -15inspect patch 0 0 -15


NETLOGO ENTITIESobserver

turtles patches

crea

tes

live on


CREATE-TURTLES

observercreate-turtles 1

turtle 0


INSPECT

observer

turtle 0

inspect turtle 0


ASK AND SET

observer

turtle 0

ask turtle 0 [

] set color BLUE


ALSO FOR PATCHES

observer

ask patch 0 0 0 [

] set pcolor CYAN


TRY THIS

ask and set are general commands, everything else is

entity-specific, see Help > NetLogo Dictionary

code won‘t work because…

ask turtle 0 [ create-turtles 1]

only the observercan create-turtles

ask patch 0 0 0[ set color red]

a patch has no property color.perhaps you meant pcolor?


COMMANDS SPECIFICALLY FOR TURTLES

forward patch-units, back patch-unitsmoves a turtle in the current direction

left degrees, right degreesalters the heading of a turtle

pen-down, pen-upchanges pen-mode

try this yourself!

ask turtle 0 [forward 1]


COMMANDS SPECIFICALLY FOR OBERSERVER

clear-all erases everything

clear-drawingerases only the tracks of turtles

create-turtles number […commands…]creates the specified number of turtles and runscommands on each one of them.


ASKING ALL AGENTS

observer

ask turtles [

]

set shape „person“


ASKING ALL PATCHES

observer

ask patches [

]

set pcolor cyan


THE „WITH“ QUERY

Can address entities based on their properties

using a “with” query:

observerask turtles with [ycor > 0] [

]


MORE EXAMPLES WITH „AND“/„OR“

ask turtles with[…]ask patches with[…]

ycor > 0

ycor > 0 and xcor < 0

ycor > 0 or xcor < 0


WRITING A PROGRAM

• code is written on the „code“ tab

click on this tab


YOUR FIRST PROGRAM

to setup clear-all create-turtles

1end write this


GIVE YOUR PROGRAM A USER INTERFACE

get back to the interface

add a buttontype thishere

setup


PRESS IT!

• this will go to code and execute „setup“• the view will turn black and one turtle will

be created at the origin


YOUR SECOND PROGRAM

to go ask turtles [

set pen-mode „down“

forward 1 ]end

write this


GIVE YOUR PROGRAM A USER INTERFACE

get back to the interface

add a buttontype thishere

go

check this!


PRESS TO SEE THE DIFFERENCE

• will execute „go“ in a loop (forever)• lots of trails will appear on screen


TYPICAL NETLOGO PROGRAM LAYOUTsetup (executes once)• clear everything• set the environment

(patches)– generate or load per-patch

data • create agents (turtles)

– set shape, color, position and orientation

• set simulation time to 0– …using reset-ticks

go (called in a loop)• simulate environment

– e.g. changes to patches• simulate agent behavior

– orient and move turtles – simulate interactions

between turtles and environment

• update statistics– using e.g. charts and plots

• advance time – …using tick

see File > Models library


USER INTERFACE

instead of using constant values, e.g.:create-turtles 10

you may

1. add a slider named num-turtles

2. use that as a placeholder, i.e.create-turtles num-turtles

num-turtles


WHERE TO GO FROM HERE

• replacing hard-coded values by UI elements is always a good idea:

• after having finished, your program look like our our prototype implementation (which we present in the following slides):

produces a number

produces true or false)

lets you enter a list of values to choose from

ARTIFICIAL SOCIETIES


WHAT IS THIS

naively,• a bunch of turtles• interacting with patches• having a behaviour (both patches AND

turtles!)

…interaction (turtle-turtle, turtle-patch, patch-turtle) is the key to complex systems


INTERACTION

• per-patch data (e.g. „amount of wood“) is read or set by a turtle (e.g. get amount of wood here; set amount of wood to 0)

• per-turtle data is influenced likewise - can be read or set by a patch (e.g. if any turles here then set color to my color)

data

behaviour

actor


DATA: PER-PATCH

is written as: patches-own [ wood food ]at begin of your code. all data is initially set to zero, must explicitly

ask patches [set wood 10] in setup if you want to change that

wood = 0 food = 0


try it, e.g. using

patches-own [ value]

and going to the interface tab

YOUR TURN!


DATA: PER-TURTLE

is likewise written as:

turtles-own [ carries-wood carries-food ]

try this outto see

how it looks

carries-wood = 0 carries-food = 0


BEHAVIOUR: SETTING A PATCH VALUE

TOP VIEW

value

SIDE VIEW

1. each turtle is in exactly one patch2. it can access a value of a patch by writing

its name, e.g.: ask turtle 0 [set value (value + 1)]

try it!

+1


MORE OPTIONS

you can get a value from…

SAME PATCH PATCH AHEAD SURROUNDING PATCH


GET VALUE AT

Figure

take

n f

rom

McL

oughlin

, La

ram

ee a

nd Z

hang 2

00

9,

“Easy

inte

gra

l su

rface

s “

option code

same patch value[value] of patch-here

patch one step ahead [value] of patch-ahead 1

surrounding patches(mean, minimum or maximum)

mean [value] of neighborsormax [value] of neighborsormin [value] of neighbors


SET VALUE AT

• however, to set a value at a different patch, you must ask:

ask turtle 0 [ ask patch-ahead 1 [ set value (value + 1) ] ]• yes that‘s right you can nest asks (in fact,

you can nest almost everything)


NEED FOR INTERMEDIATE MEMORY

ask turtle 0 [ ask patch-ahead 1 [ set pcolor color ]]

pcolor

doesn‘t workwhich of these two colors do

you mean?color color


INTERMEDIATE MEMORY

ask turtle 0 [ let the-color color ask patch-ahead 1 [ set pcolor the-color ]]

use let to remember things even after nesting, like here:

the color

RED


BEHAVIOUR: SETTING TURTLE VALUES

ask patch 0 0 0 [ ask turtles-here [ set color red ]]

• remember: there can be many turtles in the same patch

color

RED

colorcolor


MORE OPTIONS

you can also set a value to…

RED

one-of turtles-here

one-of turtles-herewith [color = purple]

RED

RED

one-of turtles in-radius 2


SELECTING TURTLES

sample model:• garden.nlogo –

used as demo for selecting turtles


SO WE COME TO BREE DS

• NetLogo predefines one „breed“ of agents called turtles

• As programmer, you are free to define more breeds using the „breed“ keyword:

• breed inherits properties ofturtle (no multiple inheritence, no patch breeds)

breed [persons person]

plural singular

THANK YOU

[email protected]

Wurzer, Lorenz, Popov: „NetLogo Workshop (Part 1)“, in eCAADe 2012 Prague, Slide 1 „Netlogo First Steps (Artif. Societies) “, in Social Simulation Conference.

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