@keystonehq/alias-sampling - npm Package Compare versions

Comparing version 0.0.5 to 0.0.6

dist/index.d.ts

 type RNGFunction = () => number;
-declare class Sample {
-    private alias;
-    private prob;
-    private outcomes;
-    private rng;
-    constructor(probabilities: number[], outcomes?: any[], rng?: RNGFunction);
-    next(numOfSamples?: number): any | any[];
-    private precomputeAlias;
-    private indexedOutcomes;
-    randomInt(min: number, max: number): number;
-}
-export default function createSample(probabilities: number[], outcomes?: any[] | null, rng?: RNGFunction | null): Sample;
+export default function sample(probabilities: number[], outcomes?: any[], rng?: RNGFunction): {
+    next: (numOfSamples?: number) => any | any[];
+};
 export {};

dist/index.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-var Sample = /** @class */ (function () {
-    function Sample(probabilities, outcomes, rng) {
-        this.alias = [];
-        this.prob = [];
-        this.outcomes = outcomes !== null && outcomes !== void 0 ? outcomes : this.indexedOutcomes(probabilities.length);
-        this.rng = rng !== null && rng !== void 0 ? rng : Math.random;
-        this.precomputeAlias(probabilities);
+var precomputeAlias = function (p, n) {
+    var sum = p.reduce(function (acc, val) {
+        if (val < 0) {
+            throw new Error('Probabilities must be positive.');
+        }
+        return acc + val;
+    }, 0);
+    if (sum <= 0) {
+        throw new Error('Probability sum must be greater than zero.');
     }
-    Sample.prototype.next = function (numOfSamples) {
-        if (numOfSamples === void 0) { numOfSamples = 1; }
-        var out = [];
-        for (var i = 0; i < numOfSamples; i++) {
-            var c = Math.floor(this.rng() * this.prob.length);
-            out[i] = this.outcomes[(this.rng() < this.prob[c]) ? c : this.alias[c]];
-        }
-        return (numOfSamples > 1) ? out : out[0];
+    var scaledProbabilities = p.map(function (prob) { return (prob * n) / sum; });
+    var aliasData = {
+        prob: new Array(n),
+        alias: new Array(n),
     };
-    Sample.prototype.precomputeAlias = function (p) {
-        var n = p.length;
-        var sum = 0;
-        var nS = 0;
-        var nL = 0;
-        var P = [];
-        var S = [];
-        var L = [];
-        for (var i = 0; i < n; ++i) {
-            if (p[i] < 0) {
-                throw new Error("Probability must be a positive: p[".concat(i, "]=").concat(p[i]));
-            }
-            sum += p[i];
+    var small = [];
+    var large = [];
+    for (var i = 0; i < n; i++) {
+        if (scaledProbabilities[i] < 1) {
+            small.push(i);
         }
-        if (sum === 0) {
-            throw new Error('Probability cannot be zero.');
+        else {
+            large.push(i);
         }
-        for (var i = 0; i < n; ++i) {
-            P[i] = p[i] * n / sum;
+    }
+    while (small.length > 0 && large.length > 0) {
+        var less = small.pop();
+        var more = large.pop();
+        aliasData.prob[less] = scaledProbabilities[less];
+        aliasData.alias[less] = more;
+        scaledProbabilities[more] -= 1 - scaledProbabilities[less];
+        if (scaledProbabilities[more] < 1) {
+            small.push(more);
         }
-        for (var i = n - 1; i >= 0; --i) {
-            if (P[i] < 1)
-                S[nS++] = i;
-            else
-                L[nL++] = i;
+        else {
+            large.push(more);
         }
-        while (nS && nL) {
-            var a = S[--nS];
-            var g = L[--nL];
-            this.prob[a] = P[a];
-            this.alias[a] = g;
-            P[g] = P[g] + P[a] - 1;
-            if (P[g] < 1)
-                S[nS++] = g;
-            else
-                L[nL++] = g;
+    }
+    large.concat(small).forEach(function (g) {
+        aliasData.prob[g] = 1;
+    });
+    return aliasData;
+};
+var draw = function (aliasData, outcomes, rng) {
+    var c = Math.floor(rng() * aliasData.prob.length);
+    return outcomes[(rng() < aliasData.prob[c]) ? c : aliasData.alias[c]];
+};
+var next = function (aliasData, outcomes, rng, numOfSamples) {
+    if (numOfSamples === void 0) { numOfSamples = 1; }
+    if (numOfSamples === 1) {
+        return draw(aliasData, outcomes, rng);
+    }
+    var samples = [];
+    for (var i = 0; i < numOfSamples; i++) {
+        samples.push(draw(aliasData, outcomes, rng));
+    }
+    return samples;
+};
+function sample(probabilities, outcomes, rng) {
+    if (rng === void 0) { rng = Math.random; }
+    if (!Array.isArray(probabilities)) {
+        throw new Error('Probabilities must be an array.');
+    }
+    var n = probabilities.length;
+    var indexedOutcomes = outcomes !== null && outcomes !== void 0 ? outcomes : Array.from({ length: n }, function (_, i) { return i; });
+    var aliasData = precomputeAlias(probabilities, n);
+    return {
+        next: function (numOfSamples) {
+            if (numOfSamples === void 0) { numOfSamples = 1; }
+            return next(aliasData, indexedOutcomes, rng, numOfSamples);
         }
-        while (nL)
-            this.prob[L[--nL]] = 1;
-        while (nS)
-            this.prob[S[--nS]] = 1;
     };
-    Sample.prototype.indexedOutcomes = function (n) {
-        var o = [];
-        for (var i = 0; i < n; i++)
-            o[i] = i;
-        return o;
-    };
-    Sample.prototype.randomInt = function (min, max) {
-        return Math.floor(this.rng() * (max - min)) + min;
-    };
-    return Sample;
-}());
-function createSample(probabilities, outcomes, rng) {
-    return new Sample(probabilities, outcomes, rng);
 }
-exports.default = createSample;
+exports.default = sample;

package.json

 {
   "name": "@keystonehq/alias-sampling",
-  "version": "0.0.5",
+  "version": "0.0.6",
   "description": "A Node.js module for efficient sampling from a discrete probability distribution using the alias method.",
@@ -5,0 +5,0 @@ "main": "dist/index.js",

README.md

@@ -26,3 +26,3 @@ # Alias Method for Sampling
 ```javascript
-import { sample } from '@keystonehq/alias-sampling';
+import sample from '@keystonehq/alias-sampling';
 
@@ -39,3 +39,3 @@ // Create a sampler with specified probabilities and outcomes
 ```javascript
-import { sample } from '@keystonehq/alias-sampling';
+import sample from '@keystonehq/alias-sampling';
 
@@ -52,3 +52,3 @@ // Create a sampler with specified probabilities
 ```javascript
-import { sample } from '@keystonehq/alias-sampling';
+import sample from '@keystonehq/alias-sampling';
 
@@ -65,3 +65,3 @@ // Create a sampler without specifying outcomes (defaults to indices)
 ```javascript
-import { sample } from '@keystonehq/alias-sampling';
+import sample from '@keystonehq/alias-sampling';
 
@@ -68,0 +68,0 @@ // Custom random generator function

No alert changes

Worsened metrics

Total package byte prevSize

6733

decreased by-4.07%

Lines of code

81

decreased by-10%

No dependency changes