I have a programme that sets up a number of different breeds of turtles. Each breed needs to have a leader turtle and a follower turtle. I have assigned these as global variables as they come up a lot in the code further down.
I need to assign these variables to turtles in the breeds and then create a link from the leader to the follower. There are a lot of conditions in the interface that determine how many and which breeds are created so i cannot assign by turtle number.
I am receiving an error (not all of the time) 'turtle cannot link with itself' which i presume occurs when they overwrite the first set command and assign the same turtle to the two variables. Does anybody know a condition i can put in that will allow it to set up everytime without the error. ( I have tried if statements, is-turtle?, one-of other, other)
breed [flinks flink] ;; linked turtles that will turn away from sources
globals [
flink-leader
flink-followers]
to set-up
clear-all
setup-turtles
reset-ticks
end
to setup-turtles
create-flinks 2 [
set flink-leader one-of flinks
set flink-followers one-of other flinks
ask flink-followers [create-link-with flink-leader]
ask flink-followers [set color pink]
ask flink-leader [
setxy 10 4]
ask flink-followers [
setxy 19.5 4]
]
end
to go
fd 1
end
There would be many different ways to approach this. Here is one that doesn't stray too far from the code you have provided:
to setup-turtles
create-flinks 2
set flink-leader one-of flinks
ask flink-leader [
set flink-followers one-of other flinks
setxy 10 4
]
ask flink-followers [
create-link-with flink-leader
setxy 19.5 4
set color pink
]
end
Note that your intuition about using other to make sure that the follower(s) is/are different from the leader was correct.
To understand what was going on, you need to grasp the notion of "context" in NetLogo. Some primitives, like ask, of and create-turtles, are "context switching": one of their argument is a code block (the part between [ and ]) that runs in the context of a particular turtle. Other primitives depend on the context in which the code is running: the primitive named other, for example, will report all the agents from a given agentset, except the one in the context of which the block is running.
In your version, you wrapped most of the code inside a code block provided for create-flinks. That meant that the code block was run once for each turtle that was created. So your calls to set flink-leader, set flink-followers and so on were all run twice, each time in a different turtle context. Can you see how that was messing things up?
Keeping track of the different context in NetLogo can be challenging at first (the frequent confusion between self/myself being a case in point), but once you get it, it should become easy and natural.
One last point as an addendum. You say:
i cannot assign by turtle number
Good! Never¹ assign anything by turtle number! It leads to brittle, error prone, more complex, less general, unnetlogoish code. If you think you need to use turtle numbers anywhere in your code, come ask another question here. Someone will most likely suggest a better way to do it.
¹ Well, almost never.
Related
This is the code of a 2 player game that I manipulated
o play-the-game
if (any-friends-nearby?) [gain-energy]
if (any-opponents-nearby?) [fight-opponent]
end
to-report any-friends-nearby?
report (any? (turtles-on neighbors4) with [breed = [breed] of myself])
end
to-report any-opponents-nearby?
report (any? (turtles-on neighbors4) with [breed != [breed] of myself])
end
to gain-energy
set similar-nearby count ( turtles-on neighbors4 )
with
[color = [color] of myself]
set total-nearby count (turtles-on neighbors)
;
;
if (similar-nearby >= total-nearby - similar-nearby)
[set energy energy + 5]
end
to fight-opponent
let my-breed [breed] of green-players
let my-color [color] of green-players
let opponent-breed [breed] of red-players
;
;;
ask my-breed
[check-random-winner]
end
to check-random-winner
let pick random-float 2
let winner nobody
ask turtles
[if winner = nobody
[ ifelse size > pick
[set winner self ]
[set pick pick - size] ] ]
end
to change-opponent
ask red-players
[ set breed green-players
set color green ]
end
Sorry if it's a bit long but when I setup up and then press go "ASK expected input to be an agent or agentset but got the list [green-players...]"
How can I fix this?
Also I'm very new to Netlogo and StackOverflow, apologies if I haven't asked my question properly.
The error message tells you that you are passing a list (more specifically, a list of breeds) to ask, when it comes to ask my-breed.
This is because the my-breed local variable is determined by
let my-breed [breed] of green-players
Let's see what we have there:
breed is a turtles-own variable: it holds the turtle's breed, and being an agents' variable can be used as a reported in the of construct (see below).
of is a reporter: it takes a reporter (normally an agents' variable) on its left (in your case: breed) and either an agent or an agentset on its right (in your case: green-players). What of reports (i.e. what it outputs) is...
... a single value if there is an agent on the right.
... a list of values if there is an agentset on the right*.
*Think about it: if I ask the color of your eyes (you are a single person, i.e. a single agent), you will tell me a single color. But if I ask the color of your friends' eyes (your friends are a group of people, i.e. an agentset), the only way for you to answer my question is to tell me a list of colors.
green-players is an agentset: all of the agents whose breed is green-players (note that for NetLogo green-players is an agentset even if it contains 1 or 0 agents).
From this, we can see that in this case of reports a list of breeds, because it reports the breed of every agent that is part of green-players, hence it will report the list [green-players green-players green-players green-players ... ] which is as long as the number of green-players in the model. You can verify this by clicking setup and then running [breed] of green-players in the Command Center.
This is a list of breeds (which can also be seen as a list of agentsets), which is not an agent or an agentset (which are the only possible targets of ask).
((note that the exact same thing happens with let my-color [color] of green-players and let opponent-breed [breed] of red-players))
So, how do you construct an agentset based on a variable? The most common way to do it is by using with (read here why).
But how can you fix your code? I don't know because I don't understand what you want to achieve.
I am not sure how you would want to use it in the code you posted, as I'm not even sure you need to use ask in fight-opponent (let alone ask an agentset).
Your fight-opponent procedure is such that, apart from the problem we just discussed, the "my-" things (i.e. my-breed and my-color) always refer to the green players while opponent-breed always refers to the red players - even if fight-opponent is run by a red player! And also, it is not clear what you want to achieve with the check-random-winner procedure and if you want this procedure to be ran by an entire breed. These things make it quite confusing to understand how you could want to fix the fight-opponent procedure.
For example: who do you want to run the check-random-winner command?
A combination of two things would be beneficial: develop your model one step at a time and make sure that every new little piece of code does exactly what you expect it to do; also, when you ask for how to fix something it is useful that you explain what you want your code to do. By doing these two things I believe it will be a lot easier to answer your questions
I'm trying to implement YOYO leader election algorithm in netlogo
first step in this algorithm is to orient links ( direct link )from the minimum to the maximumbut between neighbors only !
I tried the command
[`ask turtles with [ [ who ] of self < [who] of one-of link-neighbors ]
create-direct-to turtle [who] of one-of link-neighbors ]`
this creates direct link from min to max ( neighbors ) but also creates a direct link from max to min ( neighbors )
and I don't know what's wrong :(
here's a screenshot , if you notice theres' a direct link from 0 to 2 and also from 2 to 0 and my goal is to have only from 0 to 2
Your problem is that every time you do one-of, it randomly selects. So you test against a random link-neighbor in the first line, find it's true and then randomly select a link-neighbor to connect to.
[ ask turtles with [ [ who ] of self < [who] of one-of link-neighbors ]
create-direct-to turtle [who] of one-of link-neighbors
]
More generally, this seems an odd way to achieve your goal. To start with, link-neighbors are the turtles that the turtle is already linked to. link is the generic name for all link breeds (I think you have created a breed called direct-link).
I am not entirely clear what you mean by minimum and maximum since your code is just from smaller to larger who value, regardless of what other who values are available. If you want to create a link from every turtle to every turtle with a higher who value, here is some code:
ask turtles
[ let targets turtles with [who > [who] of myself]
create-links-to targets
]
In general, it is bad practice to use who in NetLogo code. who is a completely arbitrary identifier that simply tracks the order that turtles are created. If you have turtles that die, then your code may crash because it is referring to a turtle that no longer exists. Or perhaps at some point you will have two breeds of turtles - who doesn't care if your turtle is a person or a dog or a factory or...
This may be one of the very few exceptions, but you might want to think about what you are intending who to mean. For example, as this is a leadership model, perhaps you could have a variable called 'charisma' and all the links are from turtles with lower values of charisma to higher values of charisma.
The final part of my design involves me recording down anytime a car breed drives into or in netlogo terms, is on the same patch or X and Y coordinate as the people breed as they navigate across the edge of the screen. Had this been java I could've done something like
if Car.xPostion == Person.xPostion
(Do something...)
But unfortunately I do not know how to do the same in NetLogo, all I've been able to do so far is just ask the two breeds by giving every turtle a boolean variable called movable and setting them to true and the rest to false, is there anyway I can check the two coordinates of two different turtles on Netlogo? This is all I 've been able to do so far.
to record-accidents
ask turtles with [movable? = true]
[
]
If you tried something like your java approach, it would fail because turtle positions are continuous and floating numbers are nearly always not equal.
If I have understood your question correctly, you have given a boolean variable called movable? set to true for cars and false for all other breeds. You don't need to do this, turtles know their own breed so you can do ask cars.
To answer your specific question, there are several ways to approach it depending on the perspective (sort of, which agent is in charge).
You could identify patches where there are accidents:, which is the answer to your question in the title (about identifying patches with two breeds).
let accident-locations patches with [any? people-here and any? cars-here]
if any? accident-locations
[ ask accident-locations
[ <do something>
But you can also take a turtle perspective. You could start from pedestrians who have been hit. This takes advantage of the fact that turtles can automatically access the patch variables (like turtles-here) for the patch where they are located:
let hit people with [any? cars-here]
if any? hit
[ ask hit...
or from cars:
let hitters cars with [any? people-here]
if any? hitters
[ ask hitters...
I am brand new to Netlogo and am coding a world with caching animals. They will go to their caches (I set them as blue patches) if their energy value falls below 10. They can find these caches based on a random 'memory' value given to them which is used as an in-radius value. That way, they will face and go towards a cache within their in-radius memory if they are about to die. I am starting to incorporate a home-base system where the turtle remains in a smaller area with their own caches. Does anyone know how I can make a patch belong to an individual turtle? This would allow turtles to have their specific caches in their territory. I have looked into using links and breeds, but links are only between turtles and making the individual breeds for the 50+ turtles at a time seems ineffective and complex. I apologize I don't have any code attempting to have a cache (patch) belong to a turtle, I don't know where to start. Any ideas?
If you want a turtle to remember anything (patches or income or anything else), then you need to assign a variable in a turtles-own statement and then set the value appropriately. Here's some example code fragments. They won't work, and you actual code would likely look a lot different because you will need some design about the conditions under which a cache will be assigned, but they show you what a variable solution looks like.
turtles-own
[ my-caches
]
set my-caches (patch-set my-caches patch-here) ; code when a turtle finds a new cache site
If you want a patch that belongs to a turtle to make that patch unavailable to other turtles, then also set up a patch variable to store its owner.
patches-own
[ my-owner
]
ask turtles
[ if [my-owner] of patch-here = nobody [set my-caches (patch-set my-caches patch-here)]
ask patch-here [set my-owner myself]
]
I suggest you do several NetLogo tutorials, then look at some library models (and understand them) before starting your own model. You need to understand basic concepts like turtles/patches, variables, ticks before trying to build a model.
I want to add an agenset of turtles to the variable TurtlesICanSee of a certain turtle that depends on that turtles properties. For instance, in one application I want to add only the turtle itself to TurtlesICanSee, in another application I want to add the two turtles (if there are any) with adjacent who-numbers (the turtle's own who-number + or - 1).
If I can figure out the first application by using who-numbers I think I can extend that to second application. However, I cannot figure out the first.
I tried
ask turtles [
set TheTurtlesICanSee turtles with [who = ([who] of self)]
]
but this fills the TheTurtlesICanSee of each turtle with every turtle.
I think I understand why; NetLogo thinks that I want every turtle x that has the same who-number as itself (x), i.e. every turtle. But I don't. For every turtle x I want every turtle y that has the same who-number as x.
Can anyone help me with this? Note that the solution that I need to the first application is one that can be generalized to the second. So not any way of adding a turtle to one of its own variables will do. I need a form of self-reference involving who (or a good argument against doing it this way I guess, but preferably the former).
Your code needs only a slight alteration to work, as follows:
ask turtles [ set TheTurtlesICanSee turtles with [who = [who] of myself] ]
Note the substitution of myself for self; http://ccl.northwestern.edu/netlogo/docs/dictionary.html#myself has an explanation of the difference.
But actually there's no need to involve who numbers. It's almost never necessary to use who numbers in NetLogo; there's almost always a simpler, more direct solution. A simpler solution is:
ask turtles [ set TheTurtlesICanSee turtles with [self = myself] ]
But actually it isn't necessary to use with at all. We can use turtle-set to build the desired agentset directly:
ask turtles [ set TheTurtlesICanSee (turtle-set self) ]
This is the solution I would recommend, for clarity and brevity, but also because it will run faster, since it doesn't involve iterating over the set of all turtles, as the with-based solutions do.