I am having trouble with summing lists of all turtles and am not sure where I am going wrong.
For instance, in the following code I would like to show the total number of apples among all the turtles. Every time I run the code I get a value of 0, when it should in theory be 100. I am not sure what the error is. Any assistance would be much appreciated!
turtles-own [ apples ]
to test
clear-all
create-turtles 5 [
set apples []
set apples lput 20 apples
]
show sum [apples] of turtles
end
The following code and test should sum all the numbers in all the turtles' lists.
turtles-own [ apples ]
to test
clear-all
create-turtles 5 [
set apples []
set apples lput 20 apples
set apples lput 10 apples
]
ask one-of turtles [set apples lput 30 apples]
show sum map sum [apples] of turtles ; here's the key command
end
map sum [apples] of turtles sums the number in each turtle's list and puts those sums in a list, and then the first sum adds them all up. I made one turtle's list longer than the others' just to be sure that all the lists do not need to be the same length.
Hope this helps,
Charles
Related
I want to write in Netlogo that a certain percentage of the agent's population has this attribute. How do I do that in NetLogo?
So far, in a toy model, I do it manually. i.e: ask n-of 740 households [set composition 1] when in fact I want to say: ask 8% of the households to set composition 1.
There are two ways. I will call them ex-ante and ex-post.
Ex-ante
A frequent approach is to let each agent have a certain chance (expressed as the percentage value) of doing something. In this case you will use the random-float command in combination with your percentage value, which is the standard way to make things happen in NetLogo according to a certain probability (see here, or also see just random if you're working with integers). It can be used directly within the create-turtles block of commands:
globals [
the-percentage
]
turtles-own [
my-attribute
]
to setup
clear-all
set the-percentage 0.083 ; In this example we set the percentage to be 8.3%.
create-turtles 500 [
if (random-float 1 < the-percentage) [
set attribute 1
]
]
end
This means that you will not always have the exact number of turtles having that attribute. If you check count turtles with [attribute = 1] on multiple iterations, you will see that the number varies. This approach is good if you want to reproduce the probability of something happening (over a population of agents or over time), which is the case for many uses of NetLogo models.
Ex-post
The ex-post approach follows the logic that you more or less expressed: first you create a number of turtles, later you assign to them the attribute. In this case, you simply need to treat the percentage as in any other mathematical expression: multiply it by the total number of turtles to get the relevant turtles:
globals [
the-percentage
]
turtles-own [
my-attribute
]
to setup
clear-all
set the-percentage 0.083
create-turtles 500
ask n-of (count turtles * the-percentage) turtles [
set attribute 1
]
end
With this approach, you will always have the exact same number of turtles with that attribute. In fact, if you run count turtles with [attribute = 1] on multiple iterations you'll see that the result is always 41 (500 * 0.083 = 41.5, in fact if the number passed to n-of is fractional, it will be rounded down).
I would like to apply some process stochastically, but the order matters, or rather it should be done at random, how can I select a set of the same turtles to "treat" but to do it such that each tick, the order is random?
ask turtles [
;; apply a process to turtles, but not all turtles will get something as the pool of energy may have run out by the time they are selected.
]
Elements of agentsets (such as turtles) are always returned in a random order. Each time you use ask with an agentset, it will ask them in a new, random order. From the docs on agentsets:
An agentset is not in any particular order. In fact, it’s always in a random order. And every time you use it, the agentset is in a different random order. This helps you keep your model from treating any particular turtles, patches or links differently from any others (unless you want them to be). Since the order is random every time, no one agent always gets to go first.
And here is a quick example to demonstrate. If you run it in the Command Center you'll see the who numbers will be different each time you ask them to be shown.
to test
clear-all
create-turtles 10
show "Asking once..."
ask turtles [ show who ]
show "Asking a second time..."
ask turtles [ show who ]
end
And here is an example showing an energy pool that will be randomly used until it is gone. Note the turtles that will get to use it are whichever happen to come first out of the agentset for ask:
to test-pool
clear-all
let energy-pool 1000
create-turtles 100
ask turtles [
; can only act if some energy is left...
ifelse energy-pool > 0 [
let energy-use (min (list random 100 energy-pool))
set energy-pool (energy-pool - energy-use)
show (word "I used up " energy-use " energy points! " who " Only " energy-pool " points left")
] [
show (word "No energy left for me! " who)
]
]
end
I am trying to create a code that will allow me to get the who numbers of 10 turtles and store them in a list. However, the "who" number can only be added to the list if it has not been added to the list before.
I have to use the "foreach" command to check if the number has already been added to the list.
Any suggestions on how to do so?
My code:
turtles-own [contact-list]
to setup
clear-all
create-turtles 10 [
set contact-list []
print who
]
reset-ticks
end
to go
ask turtles [
set contact-list lput [who] of one-of other turtles-here contact-list
foreach contact-list[
; this is where the command goes
]
print contact-list
]
end
Might it be easier to add all the who numbers to the list and then use the remove-duplicates primitive to remove the duplicate numbers? I assume that you have a reason for putting who numbers into the list rather than having a list of the agents themselves, or an agentset. In general, who numbers are to be avoided.
Is there a way to ask up to a certain number of patches? For example, ask up to 100 patches but there are only 50 available, so the action takes on this 50 patches. Thanks.
The way to do this at the moment would be something like:
to-report at-most [n agents]
report ifelse-value (n <= count agents) [ agents ] [ n-of n agents ]
end
You can then say ask at-most 100 patches [ ... ] and you will get what you want.
Note that this doesn't work if there is a chance that your variable contains nobody instead of an agentset. In that case, you can convert nobody to an agentset using patch-set, turtle-set or link-set, depending on the type of agent you expect it to contain. For example:
ask one-of turtle-set other turtles-here [ ... ]
Note that the need to jump through all these hoops might disappear in the near future. There is currently an open proposal to add a primitive to NetLogo for handling these cases: https://github.com/NetLogo/NetLogo/issues/1594.
I know that monitors are updated several times per second, and that can be helpful when checking the output of a model; however, that is not the case for my model, it just weighing it down.
I am trying to plot data from a monitor. I want the monitor to only update the reporter once per tick, if possible.
My model currently functions but it is bogged down updating multiple times a second. I was hoping someone could help me minimize my model's computational effort by updating once per tick.
sample of current code:
globals [initial-patch0-health patch0-health intial-patch2-health patch2-health]
patches-own [ptype penergy max-penergy alive?]
to setup
clear-all
set patch-health 0
ask-patches [
setup-patches
]
reset-ticks
end
to setup-patches
let temp random 100
if temp <= 50 [
set ptype 2
set max-penergy random-in-range 0 5
set alive? true
]
if temp > 50 and temp <= 75 [
set ptype 0
set max-penergy random 10
set alive? true
]
set penergy max-penergy
set patch2-health (ptype2-health)
set patch0-health (ptype0-health)
end
to go
ask-patches
update-patch-health
tick
end
to patch-health
if ptype = 2[
set patch2-health (ptype2-health)
]
if ptype = 0 [
set patch0-health (ptype0-health)
]
end
to-report ptype2-health
report [penergy] of patches with [ptype = 2]
end
to-report ptype0-health
report [penergy] of patches with [ptype = 0]
end
My monitors and plot read (same for patch2-health):
sum (initial-patch0-health)
and
plot sum (patch0-health)
I use sum in this situation because the reporter delivers a list.
For context, I am doing a simple "sheep-wolf predation" style model but I want to monitor the initial grass health vs grass health over time, with multiple grass types (ptype). I have turtles but did not include that code here. Let me know if you need more code from me.
This code gives me the output I desire just at the cost of speed. I figured only reporting once every tick would save some computing time. Any suggestions for cleaning and speeding it up?
Your code example is not usable to me (undefined variables, patch0-health is not output from a reporter, other errors)- check the MCVE guidelines. With that in mind, I'm having trouble replicating the issue you describe- I ran a few profiler tests with a monitor present and not present, and didn't get any difference in runtime. With this setup:
extensions [ profiler ]
globals [ patch-turtle-sum profiler-results]
to setup
ca
ask n-of ( ( count patches ) / 2 ) patches [
set pcolor red
]
crt 1000 [
setxy random-pxcor random-pycor
]
set profiler-results []
reset-ticks
end
to profile-check
repeat 20 [
profiler:start
repeat 20 [
go
]
set profiler-results lput profiler:inclusive-time "go" profiler-results
profiler:reset
]
print profiler-results
end
to go
ask turtles [
fd 1
]
tick
end
to-report patch-turtle-sum-report
report sum [count turtles-here] of patches with [ pcolor = red ]
end
I ran the profile-check procedure from the interface, once with a monitor that monitors patch-turtle-sum-report present (mean go inclusive time: 678.59 ms) and once without (mean go inclusive time: 678.56 ms)- no detectable difference. However, I'm not sure if profiler accounts for monitor, so maybe that assessment is just not useful in this case. It could also be that the number of patches you're dealing with is quite large (in my test example I was doing 100 X 100 patches) so that the calculations get bogged down.
I wonder if you could get around your issue by using a monitor that just reports a variable that you manually calculate once per tick (instead of a to-report reporter)- eg to follow my example above, monitor a variable that is updated with something like:
set patch-turtle-sum sum [count turtles-here] of patches with [ pcolor = red ]
That way you control when the calculation is done, which may speed up the model if the calculation is what's actually slowing down your model.