CODEWITHSUNDEEP
netlogo
user1659936
user1659936

Reputation: 263

How to create link with a random agent in netlogo

I have some agents on lattice. If we consider an agent $i$, then I will assign different probabilities to all remaining agents depending on agent $i$ characteristics. Now my goal is to pick one of agent $j$ from the remaining agents with specified probabilities and create link from agent $i$ to agent $j$. This I have to do for all agents lattice. [ each time the probabilities change according to the different agents $i$] Can some one help how to implement this on netlogo. Thanks.

Upvotes: 0

Views: 718

Answers (1)

Alan
Alan

Reputation: 9620

If you do not constrain the problem more, computation will get expensive. Here is the basic idea, assuming you have an assign-probabilities reporter:

to form-links ;;turtle proc
  let %others [self] of other turtles ;;list of other turltes
  let %p assign-probabilities %others
  let %idx random-index %p
  create-link-with item %idx %others
end

to-report random-index [#p] ;;input probability dist as list
  let %draw random-float 1
  let %cum-p item 0 #p
  let %ct 0
  while [%draw > %cum-p] [
    set %ct (%ct + 1)
    set %cum-p (%cum-p + item %ct #p)   
  ]
  report %ct
end

Here are some things that can help make the computations less costly. If turtles are not created or dying, you can compute the others only once during setup (and set as a turtle attribute). If the probabilities do not change over time, you can do the same with the probabilities. In the latter case, you will then probably want to compute the cumulative probabilities (once), and use a bisection algorithm to produce the random index.

Upvotes: 1

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