I have 10 turtles and I want to work on 3 of them chosen randomly.
How do I select 3 turtles randomly and save those exact turtles to use them later?
I figured how to print the list I want to save
ask n-of 3 turtles [print int (who )]
but I do not know how to save these turtles in a list.
Say you want to save your random subset in an agentset, saved-turtles. Then it would be
let saved-turtles n-of 3 turtles
If you wanted saved-turtles to be a list, then
let saved-turtles [self] of n-of 3 turtles
sort is also useful for turning an agentset into a list
let saved-turtles sort n-of 3 turtles
Hope this helps,
Charles
Related
i am new to Netlogo, so i apologize if this is a trivial question. I would like to assign/copy the values of a list into patches attribute, making sure that the order of the values is respected. The following code does the opposite, that is, it copies the values of a patches attribute (attr1) into list1
patches-own [ attr1 attr2]
to setup
clear-all
ask patches [set attr1 random 10]
let patch-list sort patches
let list1 map [ p -> [attr1] of p ] patch-list
end
now, say that I would like to assign/copy the values of varX into patches attribute attr2, making sure that the order of the values is respected.
let nPix world-width * world-height
let varX (range nPix)
????
any suggestion? thanks
You can let Netlogo iterate through two lists simultanously by feeding the anonymous procedure two inputs. To do that, you need to put brackets around the entire procedure.
patches-own [attr2]
to setup
ca
resize-world 0 4 0 4
end
to go
let nPix world-width * world-height
let varX n-values nPix [random 140]
(foreach sort patches varX [ [the-patch the-var] ->
ask the-patch [set attr2 the-var]
]
)
show varX
ask patches [set pcolor attr2]
end
You can also always opt for a good old while loop where you increment an index (i) within the loop and use that index to couple the corresponding items from both lists.
to go-3
let nPix world-width * world-height
let varX n-values nPix [random 140]
let patch-list sort patches
let i 0
while [i < nPix] [
ask item i patch-list [set attr2 item i varX]
set i i + 1
]
show varX
ask patches [set pcolor attr2]
end
I have to do some operations in netlogo using Lists. While i can do simple tasks with them i am not yet proficient enough to code my current requirements.
I have a scenario where turtles have variables called Current-Age and Previous-Age. And turtles can be born and die if they don't meet a certain threshold.
I want to implement the following formula for each patch.
Best-list = (-1/Previous-Age) * (Distance between Patch & Turtle) for all the turtles
Best = Min [ Best-list]
I know the steps involved but have been unsuccessful in coding them. Following are the steps:
Create a list with all the current turtles that are alive
Create a second list which contains the Previous-Age
Create a third list with the distance between an individual patch and each of the live turtles
Then create another list with the output from the the Best-List formula for all the turtles in the list
Finally find the Min value in the list and store the name/who# of turtle with the minimum value in a separate variable called Best-Turtle
This is the code that i tried but didn't work.
set turtle-list (list turtles)
set turtle-age-list n-values length(turtle-list) [0]
set turtle-patch-dist-list n-values length(turtle-list) [0]
set best-list n-values length(turtle-list) [0]
ask patches[
foreach turtle-list(
set turtle-age-list replace-item ?1 turtle-age-list Previous-Age of turtles with [turtle= ?1]
)
]
I couldn't proceed to the next steps since the above code itself was not correct.
Would appreciate help with the code, thanks in advance.
Regards
First, lists are probably not the simplest way to do this. However, if you must use lists for some reason, I think what you're asking for is possible. I'm not exactly sure what you mean with best- are you trying to have each patch assess which turtle is the best turtle for that patch, and store that variable in a global list? I'm going to assume that's what you mean, but if I'm misunderstanding I think you can adapt what I do here to what you need.
First, any list passed to foreach must be the same length. So, since you mean to do this per-patch, make sure that every patch calls the procedure of list creation, not just for checking the lists. Next, review the dictionary for n-values- the syntax for the reporter means you need to use the reporter you're trying to receive- using n-values length(turtle-list) [0] will just give you a list of zeroes that is the same length as the number of turtles.
So each patch needs to create these lists- make sure you either define the patches-own for the list variables, or just use let to define the lists inside the procedure. You would need a list of ordered turtles, their previous ages, and the distance from the patch calling the procedure to each turtle. Next, you can create a list that generates a value according to your formula. Then, you can use the position primitive to find the location of the minimum value in your formula-generated list and use that to index the turtle with that value.
It might look something like
to numerical
set best-turtle []
ask patches [
let turtle-list (sort turtles) ;;; list of sorted turtles
let turtle-prev-age-list n-values length(turtle-list) [ [i] -> [pre_age] of turtle i ] ;;; list of previous ages of turtles, in same order as above
let turtle-patch-dist n-values length(turtle-list) [ [i] -> distance turtle i ] ;;; list of distance from this patch to each turtle, in same order
set best-list n-values length(turtle-list) [ [i] -> ( ( -1 / ( item i turtle-prev-age-list ) ) * ( item i turtle-patch-dist ) ) ] ;;; list of calculated values for each turtle
let best-position position (min best-list) best-list ;;; gets the index of minimum value
set best-turtle lput item best-position turtle-list best-turtle ;;; adds the best turtle for this patch to the global list of best turtles
]
end
The above procedure assumes that your turtles have a pre_age variable, patches have a best-list variable, and the list of each patches 'best turtle' is held in the global variable best-turtle. From there, you can use foreach to ask turtles in the list to do something. Note that if a turtle's previous age is 0, you will get a divide by zero error.
turtles-own [age previous-age]
to-report evalfrom [_patch]
report (- distance _patch) / previous-age
end
to test
ca
crt 25 [
set age (10 + random 75)
set previous-age age - random 10
]
print min-one-of turtles [evalfrom (patch 0 0)]
end
I am barely starting to use netlogo, and I created a model in which my agents have a list referencing a unique value for all (so its length is equal to the number of agents present at time t and the item 1 in the list corresponds to the value of turtle 1). I don’t manage to update the list when a new agent is born. How can I do that?
Regards
It sounds like you want something like this:
turtles-own [listOfTurtleVals val]
to init-turtle
set val random-float 1 ;just for illustration
set listOfTurtleVals ([val] of other turtles)
end
Then just run init-turtle on each turtle you create.
Alteratively you might have meant this:
globals [listOfInitialVals]
turtles-own [val]
to init-turtle
set val random-float 1 ;just for illustration
set listOfTurtleVals (lput val listOfInitialVals)
end
I am looking to add patch variable values to a list of empty lists. The patches are divided into different zones, and I'm trying to see how certain patch variables differ by zone.
I have an empty list of lists (actually contains 12 lists, but for simplicity):
set mylist [[] [] [] []]
And a list corresponding to the different zones:
set zone-list [1 2 3 4]
Here's how I'm trying to build the lists:
(foreach mylist zone-list [set ?1 lput (sum-zone-variable ?2) ?1])
to-report sum-zone-variable [ n ]
report (sum [patch-variable] of patches with [zone = n])
end
When I run this, mylist stays empty (ie unchanged). I think the problem is with the foreach statement, but I can't figure out what it is. Any help?
I can see the thinking behind foreach mylist [ set ?1 ... ], but NetLogo doesn't work that way. set ?1 ... has no effect on the original list. NetLogo lists are immutable, and ?1 is not a reference to an updatable location in a list — it's just a temporary variable into which a value has been copied. So set ?1 ... is something you will basically never write.
If I understand your question correctly, the relevant primitive here is map. This should do the job:
set mylist (map [lput (sum-zone-variable ?2) ?1] mylist zonelist)
Your basic approach is ok except that you must assign to a name. E.g.,
globals [mylist zone-list n-zones]
patches-own [zone zone-variable]
to setup
set n-zones 4
set zone-list n-values n-zones [?]
ask patches [set zone one-of zone-list]
set mylist n-values n-zones [[]]
end
to go
ask patches [set zone-variable random-float 1]
foreach zone-list [
let total sum [zone-variable] of patches with [zone = ?]
let oldvals item ? mylist
set mylist replace-item ? mylist (lput total oldvals)
]
end
However, you might want to use the table extension for this.
now i have the next problem. Suppose i have a list with diferent numbers for example :
let mylist [3 7 12 24 32 54 21 19]
And i want to use this list of numbers like the who of turtles. More accurately , i want that only the turtles that his who is equal to of any of the numbers of the list, do a procedure. I tried to applying directly the "with" command like this: ask turtles with [who = mylist] but is not working and i think that the problem is that i am working with a list not a specific value. Any suggestions?
You can use the foreach statement and then ask every turtle with that number. Example
let mylist [1 2 3]
foreach mylist [ ask turtle ?1 [to do some stuff] ]