weighted rand-nth proposal

[Edward Knyshov]

Hi.
Weighted selection over collection is quite often in different fields.
From cluster discovery to generation of procedural content in games.
What I would like to propose is a new double-arity rand-nth function with arguments [coll weight].
It's supposed to be used like that:

(def coll [{:weight 2 :value 1}
           {:weight 5 :value 1}
           {:weight 7 :value 1}])

(rand-nth coll :weight)

Any thoughts?

[Linus Ericsson]

A very similar function is availiable in clojure.data.generators:

https://github.com/clojure/data.generators/blob/master/src/main/clojure/clojure/data/generators.clj#L73

/Linus

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[Alex Miller]

I do not see a strong argument for this being in core. 

[Ghadi Shayban]

Edward,

I don't represent core but I agree with Alex.  This does come up a bunch (it was in Rich's old ants.clj) demo.  Little know, but here is a gist of an O(1) implementation of weighted rand using Vose's "alias method".

[Edward Knyshov]

Thank you for your answers. I appreciate it. Generator looks good. I just didn't know it exists.