random-weighted-choice

Node.js module to make a random choice among weighted elements of table.

Random Weighted Choice

Node.js module to make a random choice among weighted elements of table.

With npm do:

$ npm install random-weighted-choice

Although you can add several times the same id

var rwc = require('random-weighted-choice');
var table = [
    { weight: 1, id: "item1"} // Element 1
  , { weight: 1, id: "item2"} // Element 2
  , { weight: 4, id: "item3"} // Element with a 4 times likelihood
  , { weight: 2, id: "item1"} // Element 1, weight added with 2 => 3
];
var choosenItem = rwc(table);
var choosenUnlikely = rwc(table, 100); // The last shall be first
var choosenDeterministically = rwc(table, 0);

It is better to not use the same twice, if you want a temperature other than the default one (50).

var rwc = require('random-weighted-choice');
var table = [
    { weight: 1, id: "item1"} // Element 1
  , { weight: 1, id: "item2"} // Element 2
  , { weight: 4, id: "item3"} // Element with a 4 times likelihood
  , { weight: 2, id: "item4"} // Element 4
  , { weight: 2, id: "item5"}
];
var choosenItem = rwc(table);
var choosenUnlikely = rwc(table, 100); // The last shall be first
var choosenDeterministically = rwc(table, 0);

Without temperature (second parameter) or a 50 value, likelihoods are:

{ item1: 10%, item2: 10%, item3: 40%, item4: 20%, item5: 20% }

With a temperature value of 100:

{ item1: 30%, item2: 30%, item3: 0%, item4: 20%, item5: 20% }

With a temperature value of 0, modified weights are:

{ item1: 0, item2: 0, item3: 8, item4: 2, item5: 2 }

Return the id of the chosen item from table.

The table parameter should contain an Array. Each item of that Array must bean object, with at least weight and id property.

Weight values are relative to each other.