I've made a animal behavior model involving "turtles" and "roads" and I want the model to report back to me when the turtle "crosses" a road. All I want is that it tells me when the turtle moves from a patch that is the grey color to the red color. I've included the code asking it to report this and the program has no issue with the code. To give me a visual representation of what I want it to report, I put a monitor on interface. But it always gives me a "0" for road crossings, even as I can see that my turtle has crossed roads. I would count it by hand, but it's impossible to tell for certain how many road crossings there are and this is for scientific publication. My code is as follows...
turtles-own [
road-crossings
]
to setup
clear-all
;; create turtles on random patches.
ask patch 6 -15 [
sprout 1 [
set color one-of [green]
set size 1
set road-crossings 0
]
]
ask turtles [
if [pcolor] of patch-here = 14.9 [
set road-crossings road-crossings + 1
]
]
reset-ticks
end
to go
ask turtles [
repeat 100 [
repeat 39 [
pen-down
rt random-float 360
lt random-float 360
fd random-float 1.375
]
setxy 6 -15
]
]
tick
end
Any help is appreciated! Thank you!
There are several potential problems with this that I can see.
First, road-crossings is a turtle variable, which is the correct thing to do if you want each turtle to remember how many times it crosses a road. If so, however, the monitor must report sum [road-crossings] of turtles to get the road crossings of all turtles.
Second, which I think is actually your problem: you have the turtle checking whether it crosses the road in the setup procedure rather than the go procedure. The setup procedure is only run at the beginning.
Third, you don't actually have any roads in your example code, but I suspect that's just a failure to create a proper example. I assume that there are patches with pcolor of 14.9 in your real code. If not, though, that would also cause your error. You can make sure by going into the command center and asking count patches with [pcolor = 14.9]
Related
I am trying to get my turtles to look around themselves in netlogo and select a patch with the lowest slope variable in radius 2 - and if there isn't one to just select any patch.
I check my code, and it says everything is fine, but when I run it I keep getting this error: this code can't be run by a patch - error while patch X X running ifelse - called by procedure move - called by procedure go - called by button "go"
This is my move code:
to move
ask turtles [ask patches in-radius 2
[ifelse slope < 5
[fd 1]
[move-to one-of patches in-radius 2]
]
]
end
I have already tried downhill and downhill4 but my agents seemed to get stuck at the bottom of the slope and couldn't move anywhere.
Thank you for any help and advice!
Thank you - my code now works!
Because you are asking turtles to ask patches, the code inside the ask patches is run by the patch! A patch can’t use turtle variables, and doesn’t know that you mean to refer to the variables of the turtle that asked the patch.
This is what “of myself” is for. It lets an agent (self) talk to the agent that is telling it what to do. You’ll see stuff like “set heading [heading] of myself” But that’s not what you need here.
we could use an ask patches like you are doing here, but we really don’t want them to do anything, and it’s going to make the code much more complex looking. Anyway, We just want to find a patch that meets the turtle’s needs and move to it.
So instead. We can query the nearby patches using a WITH and store the set of patches found in a “patch set” variable.
If there are any, we can move to one of them.
Else, we can just move forward.
So
To move
Ask turtles
[
;; here the turtle tells patches to test the patch’s own slope
Let good-spots patches in-radius 2 with [ slope < 5 ]
;; are there some patches that pass the test?
If-else any? Good-spots
[ ;; Yes, pick one and go there
move-to one-of good-spots
]
[ ;; No, just move forward
Fd 1
]
]
End
Edit to add : Matteo’s answer correctly identifies the actual requirement, based on the question: move directly to the flattest patch, versus what the code above does, move to one of the flatter patches, if there is one.
Move-to min-one-of patches in-radius 2 [ slope ]
As you noted, This is similar but not identical to
Downhill slope
And neither of these may prevent turtles from getting stuck in a pit. You may need more code to detect pits and jump out of them.
The problem is not about variables but about commands: you are asking patches to run forward or to run move-to, while these are turtles' commands.
Now, for the purpose of the question, there is another issue: you said that you want
turtles to look around themselves in netlogo and select a patch with the lowest slope variable in radius 2 - and if there isn't one to just select any patch
However, even if we ignore the problem about asking patches to run forward or move-to, the structure of your code implies something very different. Your code seems to intend:
Turtles, check if there are any nearby patches with slope lower than a specific threshold;
If there are, move forward in whatever direction you are already facing;
If there are not, move to a random nearby patch.
The solution below is based on the assumption that what you want is what you said, and not what your code seems to imply.
The solution is very simple and only needs min-one-of (check it here):
to move
ask turtles [
move-to min-one-of patches in-radius 2 [slope]
]
end
As a demonstration, consider this full example:
patches-own [
slope
]
to setup
clear-all
ask patches [
set slope random 10 + 5
set pcolor scale-color green slope 5 14
]
create-turtles 10 [
setxy random-xcor random-ycor
set color yellow
]
end
to go
ask turtles [
move-to min-one-of patches in-radius 2 [slope]
]
end
You will see that turtles tend to go to darker patches, that are those with lower slope.
I want to have my turtles move back and forth between a central area and their starting location. I have set the central area (patch 0 0, and its neighbouring patches). I have set these turtles to begin from random locations on setup.
Now I need them to move to the central area and be able to remember and return to their respective starting positions. Here is my attempt, but one that is not working.
ask patches
[ set target-patch patch 0 0
ask target-patch
[ set pcolor green
ask neighbors [set pcolor green]
set hold-time 5
]
]
create-turtles 10
[ set shape "car"
set size 1
set color white
setxy random-xcor random-ycor
if (patches != patches with [pcolor = green])
[ set start-position (random-xcor random-ycor)] ;; line with error
]
to go
ask turtles
[ set heading target-patch move-to target-patch
set hold-time hold-time + 5
]
ask turtles
[ if hold-time >= 10
[ set heading start-position move-to start-position]
]
end
There are several problems with your code. I strongly suggest that you code in smaller pieces. That is, add some code and make sure it works before writing the next piece. Making sure it works is not just making it through without error messages, it needs to do what you expect it to do.
On your specific question. The line if (patches != patches with [pcolor = green]) is causing an error. First, patches is the set of all patches, not just a particular patch. So you are (sort of) asking whether the set of all patches is not equal to the set of patches that are green. Is that really what you intended? If so, it is easier to simply ask whether there is any patch that is not green:
if any? patches with [pcolor != green]
or to check whether they are all green and continue if not:
if not all? patches [pcolor = green]
However, since you are asking about moving back and forth to and from the central green patches, I think you really want to have the turtle check whether the patch they happen to be located on is green. This code looks at the patch where the turtle is located (patch-here) and checks whether the color (pcolor) is green:
if [pcolor] of patch-here = green [ ]
However, one of the tricks of NetLogo is that turtles can access the variables of the patch they are on directly. Note that a patch cannot access a turtle's variables because there may be multiple turtles on the patch so the patch doesn't know which turtle you want. But a turtle can only ever be on one patch at once. So you could write:
if pcolor = green [ ]
You also need to rethink this code:
ask patches
[ set target-patch patch 0 0
ask target-patch
[ set pcolor green
ask neighbors [set pcolor green]
set hold-time 5
]
]
This suggests to me that you have misunderstood something very fundamental to NetLogo programming. You need to think from the perspective of an individual agent. Looking at this code, you first do ask turtles, so that is going to run through all the turtles in random order. Let's call them A, then B, then C and so on.
What is each turtle going to do? Everything in the [ ]. So, A sets the value of the global variable named "target-patch" to patch 0 0. Then A asks that patch to turn green, have the 8 surrounding patches to turn green, and to set the variable "hold-time" to the value 5.
So far, so good. But then turtle B does exactly the same thing - it assigns "target-patch", turns it and its neighbors green etc. Then turtle C. If you have 100 turtles, this block of code will run 100 times and do exactly the same thing each time.
I'd like to have patches count the number of turtles that have stood on them. What would be ideal is a event such as:
if turtle-lands-on-me [add one to count]
because a turtles could leave and come back and be counted twice (which is what I want) and it would avoid counting turtles who stand still twice or more (which I don't want). Is there any way to achieve this?
Thank you!
What you need is a variable for each patch (I am calling it 'landed' below). The following code assumes you want to know about the patch it lands on each time step, but ignores the ones it passes over. It also updates the counts only where the turtle changes the patch, as requested, and labels the patch with the count.
patches-own [landed]
to setup
create-turtles 20
[ setxy random-xcor random-ycor
]
end
to go
ask turtles
[ let old-patch patch-here
set heading random 360
forward one-of [0 0.5 1 3]
if old-patch != patch-here
[ ask patch-here
[ set landed landed + 1
]
]
]
ask patches [set plabel landed]
end
The problem is that a turtle can pass over multiple patches during one time step. You can see this in the example model for those turtles that move 3. If you also want them, you will need to do something like the 'Line of Sight' model in the NetLogo models library.
I'm trying to make a model that will tick a stipulated number of times and will move a maximum distance each time. I've gotten that done, but I can't figure out how to make the model show where the turtle has been using paths connecting the different locations the turtle went to.
I don't even really know if this is possible...? I've googled, searched stack overflow and looked through the Netlogo dictionary and looked through the somewhat helpful textbook I have on hand and can't find anything. I'm sure it's simple, but I just have no idea how to go about it. My current code:
to setup
clear-all
;; create turtles on random patches.
ask patch 118 28 [
sprout 1 [
set color one-of [green]
set size 10
]
]
reset-ticks
end
to go
ask turtles [
rt random-float 360
lt random-float 360
fd random-float 15
]
if ticks = 28 [return]
tick
end
to return
ask turtles [
setxy 118 28
]
end
I am new at NetLogo and I have been working on this assignment for school, and I can't seem to find an answer to one question. I do apologize if this has been answered somewhere else before.
I am trying to make two turtles. One turtle has to be moving around the area until it finds the second turtle, whereas the second turtle is staying still. I have been trying different things, and even used to wait time, but it worked for both turtles, which is not what I want.
How do I apply the code just to one turtle out of the two? And how do I make that turtle stay in one position?
Thanks for help!
Responding to your comment- yes it works with any number of turtles if you like. For example:
breed [seekers seeker]
breed [waiters waiter]
to setup
ca
reset-ticks
create-seekers 1 [
setxy random 30 - 15 random 30 - 15
]
create-waiters 1 [
set shape "circle"
]
end
to go
ask seekers [
if not any? waiters in-radius 1 [
rt one-of [ 90 0 -90]
fd 1
]
]
tick
end
If you need them to be the same breed in your model, you can assign turtles-own variables to sort them however you like.