Given: Consider force-x and force-y as the force x and y components respectively on the agent,
Aim:you want turtle to move one of 8 neighboring patches depending force-x and force-y (Normal mechanics)
Requirement: minimum if-else statements to code.
If you were sure that your forces were not big enough to push the turtle past one of the neighboring patches, you could simply use move-to and patch-at, and ask your turtle to:
move-to patch-at force-x force-y
But perhaps your forces are bigger than that, and you still want to limit the possible moves to the neighbors. Then you can use a combination of min-one-of and distance to achieve that:
let p patch-at force-x force-y
move-to min-one-of neighbors [ distance p ]
But then again, maybe you also want to account for the possibility that the forces are not big enough to push the turtle all the way a neighbor. If that is the case, you can use patch-set to add the current patch (given by patch-here) to the set of possible destinations:
let p patch-at force-x force-y
move-to min-one-of (patch-set patch-here neighbors) [ distance p ]
Related
I'm trying to model predators hunting prey through a world filled with obstacles. In an obstacle free world, the predators go on random walks until prey fall within a certain detection radius (react-D), and then move towards the prey to capture. I guess there may be several ways to handle obstacles that block line of sight, but my initial efforts are along the following lines:
ifelse any? prey in-radius react-D
[let target min-one-of prey in-radius react-D [distance myself]
face target
...move towards target if it's closer than the nearest obstacle (blue patch) ahead
]
[continue to random walk, avoiding obstacles
]
The first condition of ifelse may need another ifelse. In any case I think I just need a distance of the nearest blue patch ahead to compare with the target distance, but it's not clear to me how I can get that from patch-ahead.
It would be nicer if I could put all this into the test of the first ifelse, but something like the following doesn't allow for patches that aren't blocking line of sight to the prey:
ifelse any? prey in-radius react-D and min-one-of (patches in-radius react-D with [pcolor = blue])[distance myself] > min-one-of (prey in-radius react-D) [distance myself]
Line of sight is actually really tricky to model in NetLogo. At the moment I do it by creating a turtle (invisible, separate breed called crawler) where the agent is that is looking and have the crawler move ahead in small steps checking the colour of the patch that it is on. That goes inside a while loop and the crawler stops when it finds the wrong colour or when it gets to the target distance. the crawler has to take small steps because crossing over the corner of a patch should still block it and it's a trade-off between resolution (how small the crawler step is) against efficiency.
You can almost certainly do the same thing by creating a patch-set as the union of patches found with patch-ahead of multiple distances like 0.1, 0.2, .... and then checking any? over that patch-set
My current solution, giving patches-own [ ob ] values of 1 to all obstacle patches, then using while to detect obstacles ahead:
to detect-ahead
let dist 1
let last-patch patch-here
while [dist <= react-D] [
let p patch-ahead dist
if p != last-patch and [ob] of p = 1 [
ask p [ sprout-markers 1 [ set color yellow ] ]
set last-patch p
]
set dist dist + 1
]
end
Then it should simply be a case of comparing min-one-of the marker agent set with the target. Obviously smaller increments would be good, as JenB says.
I am working on a NetLogo project and I want my pupil turtles to move straight until they come to be on the same Y coordinate as their relevant link neighbour and from there move towards them (the link neighbour).
Note that each pupil has only one link neighbour.
This is the code that I have come up with,
to go
ask pupils [
let target one-of link-neighbors
ifelse [ycor] of myself != [ycor] of target
[
set heading 0
fd 1
]
[
face target
fd 1
]
]
tick
end
This does not work, the turtles keep moving straight. Can someone please help. I just want the turtles to get to their link neighbours, but there are walls that they must avoid.
Your issue is that ycor is a decimal value. So, For example turtle 1 may be on 3.2 and turtle 2 may be on 3.3.
Instead, I think you want to use turtles-here.
to go
ask pupils [
let target one-of link-neighbors
ifelse member? target turtles-here
[set heading 0]
[face target]
fd 1
]
tick
end
On a side note, how many link-neighbors does each target have? My concern is that let target one-of link-neighbors will reset the target each tick.
I'm trying to add a condition that doesn't allow an agent to cross over a road. The road patches are set to color red. I can't seem to figure out how to get this condition to work. I ultimately want the agent to turn around if the road is in the patch ahead. Here is my net logo code so far.
to go
ask turtles [
move
]
tick
if ticks >= 60 [stop]
end
to move
ifelse random-float 1 < q
[
ifelse random-float 1 < w
[let target-patch max-one-of neighbors [veg-suitability]
face target-patch]
[let target-patch max-one-of neighbors [pelev]
face target-patch]
]
[
ifelse [pcolor] of patch-ahead 1 = red
[lt random-float 180]
move-to one-of neighbors
ldd-normal
]
end
to ldd-normal
let ldd-distance (ldd-scale)
fd ldd-distance
end
The logic of your move procedure is a bit confused I think. First you have a random chance to either move to a patch with a higher value of a variable of interest (with the uphill primitive) or, if the random draw fails, it moves to a random neighbour. If you don't want it to move onto a red patch then you need to test if the patch that is chosen is red, but you just move it without checking.
After you have moved the turtle, you then check the colour of patch-ahead. Your problem here is that patch-ahead depends on the direction the turtle is facing, which has nothing to do with the direction it has already been moving. You either make it turn (though it may not turn enough) OR move forward. So it never actually moves away.
I can't give you an actual answer because I don't know what your logic is supposed to be. But you could look at structures like:
move-to one-of neighbors with [pcolor != red]
Or, if there are enough red patches that it is possible that there aren't any non-red neighbours (which would cause an error if you tried to move to one), you could use:
let okay-patches neighbors with [pcolor != red]
if any? okay-patches [move-to one-of okay-patches]
Another option is that you only meant to face rather than move to the patch in the first sections of code, then test whether it is facing a red patch and turn around if it is.
I am trying to build a butterfly movement model in which butterflies are attracted to patches of their host plant. This attraction is expressed as a probability which is stored in a variable called "attr-prob". If a butterfly is located within 25 m of a host-plant patch (pcolor = 9.9), it will move to the nearest host-plant patch with the probability of attr-prob.
I wrote the following code:
if (distance (min-one-of (patches with [pcolor = 9.9]) [distance myself]) ) <= 25
[if random-float 1 < attr-prob [move-to min-one-of (patches with [pcolor = 9.9]) [distance myself]]]
This code seems to be doing what I want it to do, however, when I add this part into my model, it slows it down immensely. Does anyone have any alternative suggestions for coding this that might be quicker?
I am running Netlogo in 64-bit Java.
Try something like this:
if random-float 1 < attr-prob [
let target-patch min-one-of (patches in-radius 25 with [pcolor = 9.9]) [distance myself]
if target-patch != nobody [
move-to target-patch
]
]
This should be faster for a couple reasons.
First, the fastest code is the code that never runs. So, doing the probability check at the very beginning allows you to skip computing the closest patch whenever you can.
Second, using in-radius upfront rather than checking the distance at the end reduces the number of patches that you're looking over. Basically, you'll only be checking the color and distance of the patches in the radius, rather than all of the patches in the world.
Finally, in your original code, you were finding the closest patch twice. Instead, you can store the patch in a local variable (target-patch in the code I provided) so you only have to find it once. This alone should double the speed of the code (depending on the value of attr-prob). It also increases readability.
I need some help with some coding that has me stumped!
I have flies (a turtle breed) on a field. The field has green patches (grass) and brown and grey patches (two types of dung). There is a "patches own" which is the age of the dung (green patches = 0 and brown and grey patches increase +1 per tick).
This is what I need to happen: the flies need to move to the freshest dung within a certain radius and remain there until the dung disappears. If there is no dung within the radius they must move about randomly.
The way I have been looking about it is to use some combination of an IF statement, radius function and the downhill function (however I am not sure if that lets me select a radius or not).
Any help would be greatly appreciated, thank you.
*I have recently made some advances. I can get the flies to move randomly within a radius, but I can't specify which patches within that area the flies are allowed to go to.
[move-to one-of patches in-radius 892]
I can also make it so the flies go to the patch with the lowest patches own, but cannot specify that this patch must be of a certain colour and within a certain radius.
[move-to min-one-of patches [dung-score]]*
It might help if you combine in-radius, min-one-of and with. eg:
move-to min-one-of patches in-radius 10 with [member? pcolor [brown green]] [dung-score]
if there's a chance that the with block might return an empty agentset, you might want to test for condition to avoid an error. eg:
let candidates patches in-radius 10 with [member? pcolor [brown green]]
if any? candidates [move-to min-one-of candidates [dung-score] ]