Is there any alternative to read-from-string that works in NetLogoWeb? I need to a string from an input field. The string contains some number of integers and should be converted to a list. Within NetLogo, I use this code:
to-report get-demand
report reverse sort read-from-string ( word "[" the-field-name "]")
end
However, it seems that read-from-string is not implemented yet in NetLogoWeb. Any way around?
Many thanks and best wishes,
Michal
P.S. Many thanks for developping NetLogoWeb. I really missed NetLogo plugins.
Unfortunately, we haven't yet added support for read-from-string to NetLogo Web. It probably won't be there in the near future, either.
Is the code supplied here the real code that's giving you problems? I assume that it isn't, but, if it is, you can just do this for the same effect:
to-report get-demand
report reverse sort (list the-field-name)
end
(That is, if the-field-name is what it sounds like, which would be a string containing only the name of some "field".)
I assume that your real case is more complex. I might be able to offer a better workaround if I saw the true code. Are you sure that you can't solve your problem with tasks?
I'd suggest:
to-report string-to-numbers [s]
if empty? s [ report [] ]
if first s = " " [ report string-to-numbers butfirst s ]
let pos position " " s
ifelse not is-number? pos
[ report (list string-to-number s) ]
[ report fput string-to-number substring s 0 pos
string-to-numbers substring s (pos + 1) length s ]
end
to-report string-to-number [s]
report reduce [10 * ?1 + ?2]
map [position ? "0123456789"]
explode s
end
to-report explode [s]
report map [item ? s] n-values (length s) [?]
end
Sample run:
observer> show string-to-numbers "12 345 67"
observer: [12 345 67]
I verified that this works in both desktop NetLogo and NetLogo Web.
Based on the previous answer (that the command will not be implemented soon), it seems the only solution is to implement a simple parser, i.e. something like this (works for integers separated by spaces):
to-report string-to-list [ s ]
let l []
let ss ""
let n 0
let mode "out"
repeat length s [
set ss first s
set s but-first s
if ( ( ss = " ") and ( mode = "in" ) ) [
set mode "out"
set l lput n l
set n 0
]
if ( member? ss "0123456789") [
set mode "in"
set n ( n * 10 ) + ( position ss "0123456789" )
]
]
if ( mode = "in" ) [ set l lput n l ]
report l
end
The reporter gets a string s and returns a list of integers.
Or is there any simpler way to implement it?
Just to have an up-to-date answer here, as of October 2017, NetLogo Web does support read-from-string. A case like read-from-string (word "[" the-field-name "]") should work just as in desktop and report the list value.
Related
I downloaded the modified random clusters code for generating neutral landscape models using the Millington's version of the modified random clusters approach in the NetLogo modeling commons. When I click the "generate-landscape" button, the "fill-landscape" procedure in the code causes a "Nothing named ? has been defined" error.
When I created the attached interface image and attempted to run the adjoining code below. The problem seems to be related to the question mark in the "occurrences" report function. The reduce function is not working as intended. Is there a work around for this? See interface, then code below:
ifelse ( any? neighbours with [ cluster != nobody ] ) ;; check if there are any assigned patches in neighbourhood
[
let covers []
ask neighbours with [ cluster != nobody ]
[
set covers fput cover covers ;;ask neighbours to add their covers to the list
]
let unique-covers remove-duplicates covers ;;create a list of unique covers
let max-cover-count -1 ;the number of neighbours with the maximum cover
let max-cover -1 ;the maximum cover
ifelse(length unique-covers > 1)
[
;if there is more than one unique-cover
foreach unique-covers ;for each of the unique covers
[
let occ occurrences ? covers ;count how many neighbours had this cover
ifelse(occ > max-cover-count) ;if the count is greater than the current maximum count
[
set max-cover ? ;set this as the dominant cover
set max-cover-count occ ;update the current maximum count
;---------------
to-report occurrences [x the-list]
report reduce
[ifelse-value (?2 = x) [?1 + 1] [?1]] (fput 0 the-list)
end
;---------------
The code is suppose to generate a neutral landscape model using the modified random clusters approach developed by Saura and Martinez-Millan (2000). However, the error "Nothing named ? has been defined" error the code from running smoothly. Looking forward to thoughts ...
The old ? syntax from NetLogo 5.x was replaced with the new -> syntax in NetLogo 6. See https://ccl.northwestern.edu/netlogo/docs/programming.html#anonymous-procedures
So, for example, in NetLogo 5, you would write:
foreach [0 1 2 3] [
print ?
]
in NetLogo 6, you write:
foreach [0 1 2 3] [ x ->
print x
]
A combination of Bryan's answer (first procedure) and the NetLogo Dictionary (second procedure) gives you the following. The comments indicate the new bits. Not tested.
ifelse ( any? neighbours with [ cluster != nobody ] )
[ let covers []
ask neighbours with [ cluster != nobody ]
[ set covers fput cover covers
]
let unique-covers remove-duplicates covers
let max-cover-count - 1 ; added a space around subtraction
let max-cover - 1 ; more spacing
ifelse(length unique-covers > 1)
[ foreach unique-covers
[ this-cover -> ; here's the new bit, calling ? 'this-cover'
let occ occurrences this-cover covers ; passes to the occurrences procedure
ifelse(occ > max-cover-count)
[ set max-cover this-cover ; using the name this-cover again
set max-cover-count occ
And for occurrences, you can take the procedure directly from the NetLogo Dictionary reduce example
to-report occurrences [#x #the-list]
report reduce
[ [occurrence-count next-item] -> ifelse-value (next-item = #x)
[occurrence-count + 1] [occurrence-count] ] (fput 0 #the-list)
end
I am using Netlogo v6.0.4 and I'm getting the following error message when I try to run sample code from an answer I found here on Stack Overflow.
Nothing named ? has been defined
In this answer the following netlogo code is proposed as an answer:
to-report split [ string delim ]
report reduce [
ifelse-value (?2 = delim)
[ lput "" ?1 ]
[ lput word last ?1 ?2 but-last ?1 ]
] fput [""] n-values (length string) [ substring string ? (? + 1) ]
end
The specific ? it does like is the first one in this section substring string ? (? + 1) .
When this answer was written in 2014, Netlogo v5 was in active use and it had a feature called tasks that were lambda methods. But in v6 tasks were replaced by anonymous-procedures.
Is that what the ? are here? How can I fix this error?
You got it in one- the ? in the versions were essentially placeholders for whatever variable was being passed to the task. The 5.3 dictionary entry for foreach has a good example:
foreach [1.1 2.2 2.6] [ show (word ? " -> " round ?) ]
=> 1.1 -> 1
=> 2.2 -> 2
=> 2.6 -> 3
In that case, foreach was taking the input list of [1.1 2.2 2.6] and iterating over it, where the ? takes the place in the command block of the current item being processed. As I understand it, the main syntactical difference in 6.X is that now you explicitly state what that placeholder is, by using the -> operator. So, the exact same idea as above, translated to 6.0 in the foreach example in the 6.0 dictionary entry, looks like this:
foreach [1.1 2.2 2.6] [ x -> show (word x " -> " round x) ]
=> 1.1 -> 1
=> 2.2 -> 2
=> 2.6 -> 3
There, you can see that the x is explicitly being defined as the placeholder. This really improves the clarity of code- you can define the placeholder however you like to be as clear and explicit as you'd like- this (over the top) example works just as well:
foreach [ 1.1 2.2 2.6 ] [ round_me -> show (word round_me " -> " round round_me) ]
If you're using multiple lists, do note that you have to surround the anonymous procedure with ( ) and your placeholder declaration with [ ]- for example:
( foreach [ 1 2 3 ] [ 10 20 30 ] [ [ a b ] -> print a * b ] )
If you're translating your code example, then, you can just focus on explicitly stating the placeholders. It also might help to break it down into the component parts to clarify- more detail in comments:
to-report split2 [ string delim ]
; split the string up into individual characters
let characters fput [""] n-values ( length string ) [ a -> substring string a ( a + 1 ) ]
; build words, cutting where the delimiter occurs
let output reduce [ [ b c ] ->
ifelse-value ( c = delim )
[ lput "" b ]
[ lput word last b c but-last b ]
] characters
report output
end
Now, to follow Nicolas' example from your linked answer, you can call that to-report to split up your text:
to read-example
let line "Example\tof\tsome\ttext"
show split2 line "\t"
end
Gives you:
observer: ["Example" "of" "some" "text"]
Hope that is helpful!
I would like to make the sum = the total of pollen recieved by a plant from other plants (Donnors) which is stored in a list of a list (own by each turtle = plant).
The following code make an error (when computing the sum):
OF expected input to be an agent or agentset but got the list
[[119.05593 50 50] [301.25853 50 50] [30.23906 50 50] [460.525845 50
50] [55.16717 50 50] [301.25853 50 50]] instead.
Does any one could help me about the mistake in the line "set Tot_pol sum ..." ?
Many thanks for your help.
to check-pol [m] ;; we check the pollen recieved by the two morphs
set Donnors [] ;; empty list of pollen donnors
ask zsps with [morph = m] ;; morph of the pollen reciever
[
set totpol 0
;; check for pollen donnors and morph for compatiblity within a radius :
ask zsps with[distance myself <= 20 and morph != m]
[
set totpol (NMaleFlowers * 100 * item round (distance myself) pollination-list) ;; the farther the less pollen
set Donnors lput [ (list totpol NMaleFlowers NFemFlowers)] of myself Donnors
]
set Tot_pol sum [ item (position 0 Donnors) Donnors ] of Donnors ;; total of pollen recieved
]
end
Luke's answer is good and should fix your problem. I suspect, however, that you are going to be doing lots of these types of sums. You may wish to set up a to-report that you can use for whichever item you want to sum over, just by passing the item number and the name of the list of lists. It would look like this:
to-report sum-item [#pos #listoflists ]
let items map [ x -> item #pos x ] #listoflists
report reduce [ [a b] -> a + b] items
end
The first line extracts the relevant item (remember index from 0) into a new list which the second line sums.
You would then use it with set Tot_pol sum-item 0 Donnors
Here's an answer that is not actually responding to your question. Instead, it is a more NetLogo-ish way of doing what I think you are trying to do with your code.
to check-pol [m]
ask zsps with [morph = m]
[ let senders zsps with [distance myself <= 20 and morph != m]
set totpol sum [NMaleFlowers * 100 * round (distance myself)] of senders
]
end
Your code gets into levels of ask that I think are unnecessary. What I think you are doing with your list is keeping track of the pollen donors. But an agentset is a cleaner approach and then you can simply pull out the information you want from the agentset using of.
Further, when you ask zsps with[distance myself <= 20 and morph != m] to set variable values in your code, then THOSE agents (not the receiving agent) are the ones having their variables changed. I think you are trying to take the perspective of the receiver of pollen, who looks around and received pollen from the other agents that are close enough. So the receiving agent should have the value changed.
This is not tested.
I'm not 100% sure what you're after here (you may want to look at the Minimum, Complete, and Verifiable Example guidelines), but if I'm reading you right you want the sum of the first item for each entry in the Donners list.
As to why your approach didn't work- NetLogo is telling you with that error that you've used of with a list, but of only works with agents or agentsets. Instead, you have to use a list processing approach. The simplest way might be to use sum in conjunction with map first in order to get what you need:
to sum-first-item
let example-list [ [ 1 2 3 ] [ 4 5 6 ] [ 7 8 9 ] ]
let sum-of-firsts sum map first example-list
print sum-of-firsts
end
To translate to Donnors, try:
set Tot_pol sum map first Donnors
That should work, but without reproducible a code example I can't check.
I have small issue with a NetLogo tutorial.
I have the following situation:
to-report get-best-action
let x xcor
let y ycor
let dir heading
let best-action 0
let best-utility -100000
foreach actions[
set heading dir
run ?
let utility-of-action get-utility xcor ycor heading
if (utility-of-action > best-utility) [
set best-action ?
set best-utility utility-of-action
]
setxy x y
set heading dir
]
report (list best-action best-utility)
end
AND...
ask patches [
foreach headings [
let x pxcor
let y pycor
let dir ?
.......
In any of the presented case, the identifier '?' is considered not defined. It should work because the identifier is used the same way even in the examples of foreach. Check https://ccl.northwestern.edu/netlogo/docs/programming.html .
Did I do something wrong? Does anybody know another solution, because I tried to use an item i and the behavior of the project has been modified. (Check the project: https://www.youtube.com/watch?v=dBDVkPjyYF4 )
I would appreciate your help. Thank you!
In NetLogo before version 6, the symbols ? ?1 ?1 and so on were used as placeholders in some primitives, especially those that processed list items.
In version 6 a new syntax was introduced using "anonymous" procedures. You can make your old code using ? or ?1, etc work with few changes by adding the new syntax elements to the statement block.
Title
Code
Single ? placeholder
Extra space added to emphasize changes
Old syntax
foreach [ 1 2 3 4 ] [ show ? ]
New syntax
foreach [ 1 2 3 4 ] [ ? -> show ? ]
Multiple ?1 ?1 placeholders
Extra space added to emphasize changes
Old syntax
(foreach [1 2] ["a" "b"][ show (word ?1 ?2)]
New syntax
(foreach [1 2] ["a" "b"][ [?1 ?2] -> show (word ?1 ?2)]
In my code all turtles own n-features represented by a n-tuple (a1,a2,...,an). where each ai can take values 0 or 1.
I have created some links between turtles. If two turtles share k-features (coordinate-wise matching) and there is a link between them then we call the link as k-link.
How can I find for each k (between 0 to n) how many k-links are there in total?
You don't tell us much about how you have structured your code, so I'm going to assume that your n-tuples are implemented as lists (which would make the most sense in NetLogo).
Here is a full example:
turtles-own [ a ]
links-own [ k ]
globals [ n ]
to setup
ca
set n 5
crt 10 [ ; create turtles with random feature lists
set a n-values n [ random 2 ]
]
ask turtles [ ; make a full network
create-links-with other turtles
]
ask links [ ; calculate k for all links
set k k-of-feature-lists ([a] of end1) ([a] of end2)
]
foreach n-values (n + 1) [ ? ] [ ; display number of k-links
show (word ? "-links: " count links with [ k = ? ])
]
end
to-report k-of-feature-lists [ a1 a2 ]
report length filter [?] (map = a1 a2)
end
Apart from k-of-feature-lists, this is fairly trivial code. What k-of-feature-lists does is to:
transform two lists of features into a single list of booleans containing a true value if the corresponding element is equal in both feature lists and false if it is not. This is accomplished using map and the concise task syntax for =;
filter the list of booleans to keep only the true values;
report the length of that filtered list, which is equal to the number of features that where the same in a1 and a2;
There are plenty of other ways to do that (some more efficient) but this one is nice and concise.