I'm constructing a model of cockle growth for fisheries. One aspect of cockle biology is predation. I want to ask a specified number of turtles in a patch to die each tick. The Dictionary doesn't really provide the answer and I don't know how to model this. Any suggestions?
Thanks a lot!
Supposing you want five turtles on each patch to die, then:
ask patches [
let limit count turtles-here
ask n-of (min 5 limit) turtles-here [
die
]
]
The use of min is necessary because if I just said n-of 5 turtles-here, I would get an error on any patches with fewer than five.
You might also write:
ask patches [
repeat 5 [
if any? turtles-here [
ask one-of turtles-here [
die
]
]
]
]
which amounts to the same thing, but the n-of version should run faster.
If you want to kill 'n' turtles (replace 'n' in the code by an integer)
to kill-n-turtles
repeat 'n' [
ask one-of turtles [die]
]
end
Related
I use the nw extension in NetLogo to create a network.
My aim is the following:
Check if any turtles are close by
If any turtles are close by (I tried with next 3 patches, but that might change), connect to them + there is an upper limit of possible links
I tried (and, I think, succeeded) to implement the approach, described here. Which means that the upper limit works. However, I am not able to only link to the turtles close by. I also need something to catch the error if no turtle is close by. I tried to use the in-radius command but for some reasons, it doesn't do what I want.
extensions [nw]
breed [ AT1s AT1]
turtles-own [ friends ]
to setup
ca
create-AT1s 20 [
setxy random-xcor random-ycor
set friends 3
set color green
get-radius-friends friends AT1s
]
end
to get-radius-friends [ x AgentT]
let lonely AgentT with [count my-links < x]
let candidates other AgentT with [ any? AgentT in-radius 3 AND count my-links < x ]
let new-links x - count my-links
if new-links > 0 AND any? AgentT in-radius 3
[ let chosen n-of min (list new-links count other candidates) other candidates
create-links-with chosen [ hide-link ]
set candidates other candidates
ask chosen [ if my-links = x [ set candidates other candidates ] ]
]
end
I also found the neighbors and the distance commands but these only consider the immediate surroundings which isn't what I need.
Actually, that's not the best question to pull from if you want to spatially restrict the turtles. And there's a serious problem with having the connection within the turtle creation block because there are no potential friends for the turtles created first. Unless you have a very large number of turtles, you probably don't need to worry about efficiency.
I also think the variable 'x' is unnecessary because you have the variable 'friends' available (which appears to be the number of links you want the turtle to have). And there is a new reporter up-to-n-of which makes the whole list and min unnecessary.
I think this does what you want. You may want to test is without the hide-link so you can see what it does.
breed [ AT1s AT1]
turtles-own [ friends ]
to setup
clear-all
create-AT1s 100
[ setxy random-xcor random-ycor
set friends 3
set color green
]
get-radius-friends 10 AT1s
end
to get-radius-friends [ #radius #breed ]
let linkers turtles with [breed = #breed ]
ask linkers
[ let new-links friends - count my-links
if new-links > 0
[ let candidates other linkers with [ count my-links < friends ] in-radius #radius
let chosen up-to-n-of new-links candidates
create-links-with chosen [ hide-link ]
]
]
end
I am trying to create links from agents (in my case, towers) with a certain property to other towers with another set of properties. Only some of them should be linked, yet when I ask the observer, it says they all seem to have that link.
to setup-links
print count towers with [ any? tower-communications ]
ask towers with [ heading = 0 ] [ ; first consider the communications between different areas
create-tower-communications-with other towers with [ heading = 0 ] ; between two towers that are still standing
in-radius tower-communication-radius ; and link towers to each other if they are close enough
with [ heading = 0 ]
[set color green]
end
print count( tower-communications with [ color = green ])
print count( towers with [ any? tower-communications ])
The first print statement gives as expected, the number of links between these pairs. The second should print out the number of towers that have a link between them, but it gives me the full number of towers in the system instead. What is going wrong? I only want the set of agents that have tower-communications with at least one other agent.
I think the problem is the way you are counting the turtles with links, not the way you are creating the links. Here is a full example (note that I took out the second with [heading = 0].
globals [tower-communication-radius]
to setup
clear-all
create-turtles 25
[ setxy random-xcor random-ycor
set heading 0
]
set tower-communication-radius 5
setup-links
end
to setup-links
print count turtles with [ any? links ]
ask turtles with [ heading = 0 ]
[ create-links-with other turtles with [ heading = 0 ]
in-radius tower-communication-radius
[set color green]
]
print count turtles
print count turtles with [ any? links ]
print count turtles with [ any? my-links ]
end
Your count is print count turtles with [ any? links ]. However, the test you are asking is whether there are any links in the model, not whether there are any links attached to the turtle (or tower). You need my-links or link-neighbors to apply to the specific turtle.
I have a network of nodes and links. This figure
is a capture of the world. The graph represents streets of a city. I have imported a shapefile with the gis extension. The gray lines are links, black dots are nodes and red dots represent people. The people move heading to the next node. In a street corner, the red dot chooses next street by examining the variable popularity owned by the link.
The links breed has a variable, popularity, whose value I would like to copy in the patches that are below.
If I try, for example, something like this to access patches under links will produce an error
ask links [show [(list pxcor pycor)] of patch-here]
Another approach can be to access links variable popularity from patches, but I do not know how to do it.
The reason why I want this is because I want to write in a file a matrix of popularity values and its position in the matrix should correspond with the position of the link in the world. Thus, the patches below the links would give me the matrix form. I have a procedure that for each patch writes the value of the patch in a file. However, I do not know how to pass the popularityvalue from the link to the patch below it.
Is there any way to copy a link owned variable to its patch?
Regards
If someone has a better way of doing this (or can simplify my code), feel free. Here is a complete working example. Copy it into an empty NetLogo model and run it to see it work.
The setup procedure just creates some nodes and links with appropriate test values and then calls the transfer-link-values procedure, which does what I think you want. The setup procedure then puts the values into the patch labels to display them and see the results.
The way the transfer-link-values procedure works is to create a turtle at one end of the link, and that turtle moves toward the other end of the link transferring the value as it goes. When it gets to the other end, the turtle dies.
patches-own [patch-popularity]
links-own [link-popularity]
to setup
clear-all
create-turtles 10 [ setxy random-xcor random-ycor]
while [ any? turtles with [not any? my-links] ]
[ let to-pair turtles with [not any? my-links]
let thisNode one-of to-pair
ask thisNode
[ create-link-with one-of other to-pair
[ set link-popularity 5 + random 5 ]
]
]
transfer-link-values
ask patches [ if patch-popularity != 0 [set plabel patch-popularity ] ]
end
to transfer-link-values
ask links
[ let start-node one-of both-ends
let this-link self
let end-node nobody
ask start-node [ set end-node [other-end] of this-link ]
let transfer-value link-popularity
ask start-node
[ hatch 1
[ face end-node
if transfer-value > patch-popularity
[ ask patch-here [ set patch-popularity transfer-value ] ]
while [ not member? end-node turtles-here ]
[ forward 1
if transfer-value > patch-popularity
[ ask patch-here [ set patch-popularity transfer-value ] ]
]
if transfer-value > patch-popularity
[ ask patch-here [ set patch-popularity transfer-value ] ]
die
]
]
]
end
Is there a way to have a population of turtles breed / die in sets instead of individually?
For example: Say for each tick I'd like one population of turtles to increase by 5 and another population to decrease by 4.
I think you can do something like this
ifelse your condition come here
[ ask n-of 4 breed_type_1 [ die ]
create-breed_type_2 5
]
[ ask n-of 4 breed_type_2 [ die ]
create-breed_type_1 5
]
I am not sure if my syntax is error-free.
I been looking for the way to place each turtle in a parcel, but I do not want to have two turtles in the same parcel. Does anybody know how to do it?. (Without using sprout).
Assuming you have more patches than turtles, all you need is:
ask turtles [
move-to one-of patches with [ not any? turtles-here ]
]
Interesting side note:
People are often tempted to stick other in there, as in:
; bad code:
ask turtles [
move-to one-of patches with [ not any? other turtles-here ]
]
but this calls other within the patch context, so it doesn't actually do anything. To achieve the desired effect of not excluding the patch that the turtle is already on, you could write:
ask turtles [
let me self
move-to one-of patches with [ not any? turtles-here with [ self != me ] ]
]
Whether or not it is worth the trouble depends on your particular circumstances.
Finally, note that:
; bad code:
ask turtles [
move-to one-of patches with [ not any? [ other turtles-here ] of myself ]
]
would not work either because turtles-here would then be called in the turtle's context instead of being called in the patch context.