CODEWITHSUNDEEP
netlogo
BiSarfraz
BiSarfraz

Reputation: 479

How to get the top 10 turtles sorted by reverse in-degree centrality?

I want to get a list of top ten turtles in terms of their degree centrality. I have tried but I am not getting the required result. In the code below, I am storing centrality in a list and then reverse sorting it. However, it is storing centralities only. I want turtles ordered in terms of their centrality. I also have tried saving turtles on the list and have used sort-by but got an error. I also have tried to get agents using turtles with max degree centrality, but the problem arises when several nodes have the same centrality. I want to do this in an efficient manner.

    globals [indeg]
    turtles-own [centrality]
    to setup
      ca
      crt 160

      ask turtles [ 
        set indeg [] 
        fd random 15
      ]
      ask turtles with [color = red] [create-links-to other turtles with [color = blue]]
      ask turtles with [color = green] [create-links-from other turtles with [color = yellow]]
      inf
    end

    to inf
      ask turtles [
        set centrality count my-in-links
        set indeg lput centrality indeg
      ]
      set indeg sort(indeg)
      print "indeg"
      print reverse(indeg)
      print max(indeg)
    end

Upvotes: 2

Views: 270

Answers (1)

Nicolas Payette
Nicolas Payette

Reputation: 14972

Here are three different ways to get that information, with potentially slightly different performance and results:

to setup
  clear-all
  create-turtles 160 [ forward random 15 ]
  ask turtles with [color = red] [create-links-to other turtles with [color = blue]]
  ask turtles with [color = green] [create-links-from other turtles with [color = yellow]]

  let top-10-a reverse sort-on [ count my-in-links ] max-n-of 10 turtles [ count my-in-links ]
  show-results top-10-a "Top ten turtles using max-n-of:"

  let sorted-turtles reverse sort-on [ count my-in-links ] turtles

  let top-10-b sublist sorted-turtles 0 9
  show-results top-10-b "Top ten turtles from sorted list:"

  let top-10-c filter [ t ->
    [ count my-in-links ] of t >= [ count my-in-links ] of item 9 sorted-turtles
  ] sorted-turtles 
  show-results top-10-c "Turtles with top ten centrality:"

end

to show-results [ turtle-list title ]
  print title
  foreach turtle-list [ t -> ask t [ show count my-in-links ] ]
end

The first (method "a") and most obvious is to use NetLogo's max-n-of primitive. That primitive gives back an agentset (not a list), so if you want an agentset, that's the way to go.

Your question seem to indicate that you ultimately want a list of turtles sorted by decreasing centrality, so you have to use reverse sort-on [ count my-in-links ] on the result of max-n-of, which is what I'm doing above.

Another approach (method "b") would be to sort all turtles by their centrality, store the resulting list in sorted-turtles variables and then take the first 10 of that. That method is a bit more intuitive but could be slower than the max-n-of method since it has to sort the whole list. Depending on how many turtles you have, however,the difference could be negligible.

One thing the first two methods have in common is that the ties are broken randomly. This means that if you have, let's say, three turtles that have a centrality worthy of position number ten in your top ten, you'll only get one of those. (Given the way you construct your network in the example from your question, this is very likely to happen.) If you want your top ten to potentially include more than 10 turtles in case of equality, you need to use method "c".

The last method sorts the whole, look at the centrality of the tenth turtle in that list, and filters the list to keep only the turtles with centrality greater or equal to that one.

Upvotes: 3

Related Questions