MIS 643 AgentBased Modeling Net Logo Summary of

MIS 643 Agent-Based Modeling Net. Logo: Summary of Manual and Dictionary

Outline 1. 2. 3. 4. 5. 6. 7. procedures variables ask agentsets breeds lists Net. Logo Dictionary

1. Procedures – with inputs • put input names in square brackets after the procedure name. to draw-polygon [num-sides len] ; ; turtle procedure pen-down repeat num-sides [ fd len rt 360 / num-sides ] end use the procedure by asking the each turtles to draw an octagon with a side length equal to its who number: ask turtles [ draw-polygon 8 who ]

Procedures – Reporters • to-report: to begin procedure • in the body of the procedure, - report to report or return the value you want to return to the caller to-report absolute-value [number] ifelse number >= 0 [ report number ] [ report (- number) ] end

2. Variables • global – observer – every agent can see or manipulate – declered - globals [total-enery] • agent variables – turtle, patch, link – for each agent one variable – turles-own [energy speed] • initial values are 0 • set for assignment – ask turtles [set pcolor red] • turtles can reach and manipulate patch variables they are currently on • of: agents can reach variables of other agents – show [color] of turtle 5 – show [xcor + ycor] of turtle 5

Variables – local variables • in procedures or blocks • Example: to swap-colors [turtle 1 turtle 2] let temp [color] of turtle 1 ask turtle 1 [ set color [color] of turtle 2 ] ask turtle 2 [ set color temp ] end

Variables - types • numeric – no distiction between integer or float • boolean – true false • string – string of characters in “” • color – from 0 to 139. 9 • agent or agentset • list • Constants – boolean – true false – mathematical – e, pi – color – red blue balck yellow

tick counter • reset-ticks • tick, tick-advance • ticks: variable

3. ask • to give commands to turtles, patches, and links • context change to turtles patches or links • Example: to setup clear-all create-turtles 100 ; ; create 100 turtles with random headings ask turtles [ set color red ; ; turn them red fd 50 ] ; ; spread them around ask patches [ if pxcor > 0 ; ; patches on the right side [ set pcolor green ] ] ; ; of the view turn green reset-ticks end

asking individual agents • asking individual agents to setup clear-all crt 3 ; ; make 3 turtles ask turtle 0 ; ; tell the first one. . . [ fd 1 ] ; ; . . . to go forward ask turtle 1 ; ; tell the second one. . . [ set color green ] ; ; . . . to become green ask turtle 2 ; ; tell the third one. . . [ rt 90 ] ; ; . . . to turn right

asking individual agents ask patch 2 -2 ; ; ask the patch at (2, -2) [ set pcolor blue ] ; ; . . . to become blue ask turtle 0 ; ; ask the first turtle [ ask patch-at 1 0 ; ; . . . to ask patch to the east [ set pcolor red ] ] ; ; . . . to become red ask turtle 0 ; ; tell the first turtle. . . [ create-link-with turtle 1 ] ; ; . . . make a link with the second ask link 0 1 ; ; tell the link between turtle 0 and 1 [ set color blue ] ; ; . . . to become blue reset-ticks end

who number • who number – every turtle has an who number stating from 0 • turtle number • <breed > number • patch x y – identified with their x and y coordinates • link who 1 who 2 – which turtles it is connecting

4. agentsets • a set of agents containing – turtles, patches or links – but not more than one type at once • • • in a random order turtles - reports agentset of all turtles patches - << << patches links - << << links also some tutrles, patches or links – turtles with color red – pathces on the positive quadrant - pxor>0 and pyor>0 – turtles-here, turtles-at, tutles-on

forming agentsets ; ; all other turtles: other turtles ; ; all other turtles on this patch: other turtles-here ; ; all red turtles: turtles with [color = red] ; ; all red turtles on my patch turtles-here with [color = red] ; ; patches on right side of view patches with [pxcor > 0]

forming agentsets (2) ; ; all turtles less than 3 patches away turtles in-radius 3 ; ; the four patches to the east, north, west, and south patches at-points [[1 0] [0 1] [-1 0] [0 -1]] ; ; shorthand for those four patches neighbors 4 ; ; turtles in the first quadrant that are on a green patch turtles with [(xcor > 0) and (ycor > 0) and (pcolor = green)] ; ; turtles standing on my neighboring four patches turtles-on neighbors 4 ; ; all the links connected to turtle 0 [my-links] of turtle 0

what can be done? • Use ask to make the agents in the agentset do something • Use any? to see if the agentset is empty • Use all? to see if every agent in an agentset satisfies a condition. • Use count to find out exactly how many agents are in the set

any? agentset – Reports true if the given agentset is nonempty, false otherwise. • Equivalent to "count agentset > 0", but more efficient (and arguably more readable). if any? turtles with [color = red] [ show "at least one turtle is red!" ]

what else can be done? • Pick a random agent from the set using one-of. • For example, • we can make a randomly chosen turtle turn green: – ask one-of turtles [ set color green ] • tell a randomly chosen patch to sprout a new turtle: – ask one-of patches [ sprout 1 ]

what else can be done? (2) • Use the max-one-of or min-one-of reporters to find out which agent is the most or least along some scale. For example, to remove the richest turtle, you could say ask max-one-of turtles [sum assets] [ die ]

max-one-of agentset [reporter] • Reports the agent in the agentset that has the highest value for the given reporter. If there is a tie • this command reports one random agent with the highest value. If you want all such agents, use • with-max instead. show max-one-of patches [count turtles-here] ; ; prints the first patch with the most turtles on it

with-max agentset with-max [reporter] • Takes two inputs: on the left, an agentset (usually "turtles" or "patches"). On the right, a reporter. • Reports a new agentset containing all agents reporting the maximum value of the given reporter. show count patches with-max [pxcor] ; ; prints the number of patches on the right edge

what else can be done? (3) • Use of to make a list of values, one for each agent in the agentset. Then use one-of • Net. Logo's list primitives to do something with the list. (See the "Lists" section below. ) • For example, to find out how rich turtles are on the average, you could say show mean [sum assets] of turtles

what else can be done? (4) • Use turtle-set, patch-set and linkset reporters to make new agentsets by gathering together agents from a variety of possible sources. • Use no-turtles, no-patches and nolinks reporters to make empty agentsets. • Check whether two agentsets are equal using = or !=. • Use member? to see whether a particular agent is a member of an agentset.

one-of agentset one-of list • From an agentset, reports a random agent. If the agentset is empty, reports nobody. • From a list, reports a random list item. It is an error for the list to be empty. ask one-of patches [ set pcolor green ] ; ; a random patch turns green ask patches with [any? turtles-here] [ show one-of turtles-here ] ; ; for each patch containing turtles, prints one of those turtles ; ; suppose mylist is [1 2 3 4 5 6] show one-of mylist ; ; prints a value randomly chosen from the list

of [reporter] of agentset • For an agent, reports the value of the reporter for that agent (turtle or patch). show [pxcor] of patch 3 5 ; ; prints 3 show [pxcor] of one-of patches ; ; prints the value of a random patch's pxcor variable show [who * who] of turtle 5 => 25 show [count turtles in-radius 3] of patch 0 0 ; ; prints the number of turtles located within a ; ; three-patch radius of the origin

of agentset • For an agentset, reports a list that contains the value of the reporter for each agent in the agentset in random order). crt 4 show sort [who] of turtles => [0 1 2 3] show sort [who * who] of turtles => [0 1 4 9]

turtle-set value 1 (turtle-set value 1 value 2. . . ) • Reports an agentset containing all of the turtles anywhere in any of the inputs. The inputs may be • individual turtles, turtle agentsets, nobody, or lists (or nested lists) containing any of the above. turtle-set self (turtle-set self turtles-on neighbors) (turtle-set turtle 0 turtle 2 turtle 9) (turtle-set frogs mice)

patch-set value 1 (patch-set value 1 value 2. . . ) • Reports an agentset containing all of the patches anywhere in any of the inputs. The inputs may be • individual patches, patch agentsets, nobody, or lists (or nested lists) containing any of the above. patch-set self patch-set patch-here (patch-set self neighbors) (patch-set patch-here neighbors) (patch-set patch 0 0 patch 1 3 patch 4 -2) (patch-set patch-at -1 1 patch-at 0 1 patch-at 1 1) patch-set [patch-here] of turtles patch-set [neighbors] of turtles

Special agentsets observer> 5 observer> 10 observer> 15 clear-all create-turtles 5 set g turtles print count g create-turtles 5 print count g set g turtle-set turtles print count g create-turtles 5 print count g print count turtles

5. Breeds • breeds of tutrles or links • behave differently – sheep or wolves • breed key word breed [volves volf] breed [sheep a-sheep] • in gnereal breed [pulural singular] • singular form - <breed> • pulural form <breeds>

• define a breed: – breed [sheep a-sheep] create-sheep, hatch-sheep, sproutsheep, sheep-here, sheep-at, sheep-on, is-asheep? . • define new variables for breed: sheep-own [. . . ] • tutle breeds – breed variable stores breed if breed = wolves [. . . ] • can be tested ask one-of wolves [ set breed sheep ] • can be changed

breeds – who numbers • who numbers assigned irrispective of breeds breed [mice mouse] breed [frogs frog] mice-own [cheese] to setup clear-all create-mice 50 [ set color white set cheese random 10 ] create-frogs 50 [ set color green ] reset-ticks end

6. Lists • single variables e. g. numeric, strings – holds one pice of information • lists – multiple pices of information • heterogenuous – boolean, number, string, agentset, list • List related primitives but-first, but-last, empty? , filter, first, foreach, fput, histogram, islist? , item, last, length, list, lput, map, member? , modes, n-of, n-values, of, position, one-of, reduce, removeduplicates, remove-item, replace-item, reverse, sentence, shuffle, sort-by, sort-on, sublist

Constant lists • e. g. set mylist [2 4 6 9] • lists within lists: [[2 4] [3 5]] • empty list: []

Building lists on the fly • list accepts two reporters run them and form a list • e. g. : list from two random numbers list (random 10) (randonm 20) • for one or mere then three reporters use paranthesis (list random 10) (list random 10)

list value 1 value 2 (list value 1. . . ) • Reports a list containing the given items. The items can be of any type, produced by any kind of reporter. show list (random 10) => [4 9] ; ; or similar list show (list 5) => [5] show (list (random 10) 1 2 3 (random 10)) => [4 1 2 3 9] ; ; or similar list

Varying number of inputs • Some commands and reporters involving lists and strings may take a varying number of inputs. In • these cases, in order to pass them a number of inputs other than their default, the primitive and its • inputs must be surrounded by parentheses. Here are some examples:

examples show list 1 2 => [1 2] show (list 1 2 3 4) => [1 2 3 4] show (list) Þ[] • special commands - default number of inputs. list, word, sentence, map, foreach.

n-values size reporter-task • Reports a list of length size containing values computed by repeatedly running the task. • If the task accepts inputs, the input will be the number of the item currently being computed, starting from zero. show n-values 5 [1] => [1 1 1] show n-values 5 [? ] => [0 1 2 3 4] show n-values 3 turtle => [(turtle 0) (turtle 1) (turtle 2)] show n-values 5 [? * ? ] => [0 1 4 9 16]

of primitieve again of primitive • take an agentset and produce a list applying the reporter to the set max [. . . ] of turtles sum [. . . ] of turtles

sentence value 1 value 2 (sentence value 1. . . ) • Makes a list out of the values. If any value is a list, its items are included in the result directly, rather than being included as a sublist. show sentence 1 2 => [1 2] show sentence [1 2] 3 => [1 2 3] show sentence 1 [2 3] => [1 2 3] show sentence [1 2] [3 4] => [1 2 3 4] show (sentence [[1 2]] [[3 4]]) => [[1 2] [3 4]] show (sentence [1 2] 3 [4 5] (3 + 3) 7) => [1 2 3 4 5 6 7]

list and sentence show => list [1 2] 3] sentence [1 2] 3 [1 2 3]

Changing list items • can't be modified • replace-item set mylist [2 7 5 “Bob” [3 0 2]] ; mylist is now [2 7 5 “Bob” [3 0 -2]] set mylist replace-item 2 mylist 10 ; mylist is now [2 7 10 “Bob” [3 0 -2]]

replace-item index list value replace-item index string 1 string 2 • On a list, replaces an item in that list. index is the index of the item to be replaced, starting with 0. • for a string, but the given character of string 1 removed and the contents of string 2 spliced

replace-item show replace-item 2 [2 7 4 5] 15 => [2 7 15 5] show replace-item 1 "cat" "are" => "caret"

adding or droping items • To add an item, say 42, to the end of a list, use the lput reporter. • (fput adds an item to the beginning of a list. )

adding or droping items set mylist lput 42 mylist ; mylist is now [2 7 10 “Bob” [3 0 -2] 42] • The but-last (bl) for short) reporter reports all the list items but the last. set mylist but-last mylist ; mylist is now [2 7 10 “Bob” [3 0 -2]]

• to get rid of item 0, the 2 at the beginning of the list. set mylist but-first mylist ; mylist is now [7 10 Bob [3 0 -2]]

• to change third item that's nested inside item 3 from -2 to 9? The key is to realize that the name that can be used to call the nested list [3 0 -2] is item 3 mylist. Then the • replace-item reporter can be nested to change the list-within-a-list. The parentheses are added • for clarity. set mylist (replace-item 3 mylist (replace-item 2 (item 3 mylist) 9)) ; mylist is now [7 10 Bob [3 0 9]]

item • item index list • item index string • On lists, reports the value of the item in the given list with the given index. • On strings, reports the character in the given string at the given index. • Note that the indices begin from 0, not 1. (The first item is item 0, the second item is item 1, on. )

item ; ; suppose mylist is [2 4 6 8 10] show item 2 mylist => 6 show item 3 "my-shoe" => "s"

Iterating over lists • foreach command • map reporter.

foreach examples (1) foreach - run a command or commands on each item in a list. foreach [1 2 3] show or foreach [1 2 3] [show ? ] => 1 => 2 => 3 foreach [2 4 6] [ crt ? show (word "created " ? " turtles") ] => created 2 turtles => created 4 turtles => created 6 turtles • In the block, the variable ? holds the current value from the input list.

foreach examples (2) foreach [1 2 3] [ ask turtles [ fd ? ] ] ; ; turtles move forward 6 patches foreach [true false true] [ ask turtles [ if ? [ fd 1 ] ] ] ; ; turtles move forward 3 patches

foreach list command-task (foreach list 1. . . command-task) • With a single list, runs the task for each item of list. foreach [1. 1 2. 2 2. 6] show => 1. 1 => 2. 2 => 2. 6 foreach [1. 1 2. 2 2. 6] [ show (word ? " -> " round ? ) ] => 1. 1 -> 1 => 2. 2 -> 2 => 2. 6 -> 3

foreach: multiple list • With multiple lists, runs commands for each group of items from each list. So, they are run once for the first items, once for the second items, and so on. All the lists must be the same length. (foreach [1 2 3] [2 4 6] [ show word "the sum is: " (? 1 + ? 2) ]) => "the sum is: 3" Þ"the sum is: 6“ =>"the sum is: 9"

foreach: multiple list (foreach list (turtle 1) (turtle 2) [3 4] [ ask ? 1 [ fd ? 2 ] ]) ; ; turtle 1 moves forward 3 patches ; ; turtle 2 moves forward 4 patches

iterating over lists - map • map - reporter. It takes an input list and a reporter name or reporter block. show map round [1. 2 2. 7] ; ; prints [1 2 3] • map reports a list containing the results of applying the reporter to each item in the input list. Again, • use ? to refer to the current item in the list.

iterating over lists – map (cont. ) show map [? < 0] [1 -1 3 4 -2 10] ; ; prints [false true] show map [? * ? ] [1 2 3] ; ; prints [1 4 9] • Besides map and foreach, other primitives for processing whole lists in a configurable way include filter, reduce, and sort-by.

map reporter-task list (map reporter-task list 1. . . ) • With a single list, the given task is run for each item in the list, and a list of the result are collectedand reported. show map round [1. 1 2. 2 2. 7] => [1 2 3] show map [? * ? ] [1 2 3] => [1 4 9]

map: multiple list • With multiple lists, the given reporter is run for each group of items from each list. So, it is run once for the first items, once for the second items, and so on. All the lists must be the same length. show (map + [1 2 3] [2 4 6]) => [3 6 9] show (map [? 1 + ? 2 = ? 3] [1 2 3] [2 4 6] [3 5 9]) => [true false true]

Lists of agents • sort and sort-by. • take an agentset as input. The result is always a new list, in a particular order. • sorting: • – turtles - list of turtles - in ascending order by who number. • – patches - list of patches sorted left-to-right, top-tobottom. • – links - list of links, sorted in ascending order first by end 1 then by end 2 any remaining ties are resolved by breed in the order they are declared in the Code tab. • descending order - reverse with sort reverse sort turtles.

Lists of agents sort-by • ordered by some other criterion • sort-by [[size] of ? 1 < [size] of ? 2] turtles • list of turtles sorted in ascending order by their turtle variable size.

sort list sort agentset • Reports a sorted list of numbers, strings, or agents. • If the input contains no numbers, strings, or agents, the result is the empty list. • If the input contains at least one number, the numbers in the list are sorted in ascending order and a new list reported; non-numbers are ignored. • Or, if the input contains at least one string, the strings in the list are sorted in ascending order and a new list reported; non-strings are ignored. • Or, if the input is an agentset or a list containing at least one agent, a sorted list of agents (never an agentset) is reported; non-agents are ignored. Agents are sorted in the same order the < operator uses.

sort examples show sort [3 1 4 2] => [1 2 3 4] let n 0 foreach sort patches [ ask ? [ set plabel n set n n + 1 ] ] ; ; patches are labeled with numbers in left-to-right, ; ; top-to-bottom order

sort-by reporter-task list sort-by reporter-task agentset • If the input is a list, reports a new list containing the same items as the input list, in a sorted order • defined by the boolean reporter task.

sort-by • The two inputs to the reporter task are the values being compared. The task should report true if ? 1 • comes strictly before ? 2 in the desired sort order, and false otherwise. • If the input is an agentset or a list of agents, reports a list (never an agentset) of agents. • If the input is a list, the sort is stable, that is, the order of items considered equal by the reporter is • not disturbed. If the input is an agentset, ties are broken randomly.

sort-by examples show sort-by < [3 1 4 2] => [1 2 3 4] show sort-by > [3 1 4 2] => [4 3 2 1] show sort-by [length ? 1 < length ? 2] ["Grumpy" "Doc" "Happy"] => ["Doc" "Happy" "Grumpy"]

sort-on [reporter] agentset • Reports a list of agents, sorted according to each agent's value for reporter. Ties are broken • randomly. • The values must be all numbers, all strings, or all agents of the same type.

sort-on examples crt 3 show sort-on [who] [turtles] => [(turtle 0) (turtle 1) (turtle 2)] show sort-on [(- who)] [turtles] => [(turtle 2) (turtle 1) (turtle 0)] foreach sort-on [size] turtles [ ask ? [ do-something ] ] ; ; turtles run "do-something" one at a time, in ; ; ascending order by size

Asking a list of agents • foreach and ask commands in combination: foreach sort turtles [ ask ? [. . . ]; end of ask ]; end of foreach • ask each turtle in ascending order by who number. • Substitute "patches" for "turtles" to ask patches in left-to-right, top-to-bottom order.

turtles • • moving tutles reporting patches from turtles obtaining information obut patche tutles towardsxy x y – returns heading form x and y • face

turtles • tutles-at dx dy – reports tutles dx dy away form turle or pathc • turtles-here <breeds>-here – reoprt tutles at patch • tutles-on agent(set) <breeds>-on agent(set) – turtles on the given agent or agent set

• back (bk) <breeds>-at <breeds>-here <breeds>-on can-move? clear-turtles (ct) create-<breeds> • create-ordered-<breeds> create-ordered-turtles (cro) create-turtles (crt) die distancexy • downhill 4 dx dy facexy forward (fd) hatch-<breeds> hide-turtle (ht) home inspect • is-<breed>? is-turtle? jump layout-circle left (lt) move-to myself nobody no-turtles of other

• patch-ahead patch-at-heading-and-distance patch-here patch-left-and-ahead • patch-right-and-ahead pen-down (pd) pen-erase (pe) pen-up (pu) random-xcor random-ycor right • (rt) self set-default-shape __set-line-thickness setxy shapes show-turtle (st) sprout-<breeds> • stamp-erase subject subtract-headings tie towardsxy turtle-set turtles-at • turtles-here turtles-on turtles-own untie uphill 4

• inspect • layout-circle • set-default-shape __set-line-thickness shapes • stamp-erase subject subtractheadings tie turtles-own untie

tutrles - creation • creating or dieing turtles or breeds • create-<breeds>, create-ordered<breeds, create-ordered-turtles (cro), create-turtles (crt), die • hatch-<breeds> sprout<breeds> • clear-turtles (ct)

• <breeds>-at <breeds>-here <breeds>on • turtle-set turtles-at • turtles-here turtles-on • no-turtles

turtles - movement • back (bk), forward (fd), jump – t forward num, t jump num • left (lt), right (rt) facexy – t face agent , t facexy num 1 num 2 – t right angle • move-to – t – move-to agent

turtles - movement • • setxy, random-xcor random-ycor home downhill, downhill 4, uphill 4 boolean – can-move,

turtles - information • • distancexy towardsxy dx dy is-<breed>? is-turtle?

turtles - information • patch-ahead patch-at-headingand-distance patch-here patch-left-andahead • patch-right-and-ahead • turtles-at <breeds>-at turtles-here <breeds>-here • turtles-on <breeds>-on – from turtles or patches to set of turtles or breeds

• pen-down (pd) pen-erase (pe) pen-up (pu) • hide-turtle (ht) show-turtle (st), showturtle (st) show-turtle (st)

patches • clear-patches (cp) diffuse 4 distancexy import-pcolors-rgb inspect • is-patch? myself neighbors 4 nobody no-patches of other patch -at patch-ahead

patches • patch-at-heading-and-distance patchhere patch-left-and-ahead patch-rightand-ahead patch-set • patches-own random-pxcor random-pycor self sprout<breeds> subject turtles-here

patches • diffuse 4 import-pcolors importpcolors-rgb inspect • patch-at patch-ahead • patch-at-heading-and-distance patchhere patch-left-and-ahead patch-rightand-ahead • patches-own random-pxcor random-pycor sprout-<breeds> subject turtles-here

• clear-patches (cp)

• distancexy • neighbors 4 • is-patch?

• no-patches patch • patch-set

agentsets • nobady • no-patches • patches patch • patch-set

• all? any? ask-concurrent at-points <breeds>-at <breeds>-here <breeds>on count in-cone • in-radius is-agent? is-agentset? is-patchset? is-turtle-set? link-heading linklength link-set

• link-shapes max-n-of max-one-of member? min-n-of min-one-of neighbors 4 • no-patches no-turtles of one-of other patch-set patches sort-by sort-on turtle-set turtles with • with-max with-min turtles-at turtleshere turtles-on

Important • other of with • self myself

Control flow andlogic • and ask-concurrent carefully end error-message every if ifelse -value let loop not or • repeat report runresult ; (semicolon) set stop startup to to-report wait while • with-local-randomness withoutinterruption xor

Control flow andlogic • • carefully error-message runresult ; (semicolon) startup every wait with-local-randomness withoutinterruption

assignment • let set

condition • • if ifelse-value and not or xor

flow control • • ask-concurrent to to-report end report stop while loop repeat

Task • filter foreach is-command-task? isreporter-task? map n-values reduce runresult sort-by task

List • but-first but-last empty? filter first foreach fput histogram is-list? item last length list lput map • member? modes n-of n-values of position one-of reduce removeduplicates remove-item • replace-item reverse sentence shuffle sort-by sort-on sublist

String • Operators (<, >, =, !=, <=, >=) butfirst but-last empty? first is-string? item last length member? • position remove-item read-from -string replace-item reverse substring word

Mathematical (1) • Aritmetic operators: – +, -, *, /, mod, ^; =; !=, <, >, <=; >=

Mathematical (1)

Mathematical (1) • functions: take a number, proces it and reports another number – abs, acos, asin, atan, celling cos e – trigonometric/inverse trigonometirc: cos, sin, ta acos, asin, atan – logarithmic/exponentioal: exp, ln, log- e – Verious funcitons: ceillin, floor, int, precision, remainder, round, sqrt, substract -headings

– boolean: is-number? – random number generations: random, random-exponential, randonm-floa random-normal, random-poisson, randomseed, new-seed

Mathematical (2) • primitives taking a list of numbers and reporting a number – mean, max, min, median, modes, standartdeviation, variabce, sum • constants: – e, pi