140 lines
3.7 KiB
JavaScript
140 lines
3.7 KiB
JavaScript
var random = {
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twister: null,
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init: function (seed) {
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if (seed == null || seed === undefined) {
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seed = new Date().getTime();
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}
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this.twister = new MersenneTwister();
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this.twister.seed(seed);
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},
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number: function (limit) {
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// Returns an integer in [0, limit]. Uniform distribution.
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if (limit == 0) {
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return limit;
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}
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if (limit == null || limit === undefined) {
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limit = 0xffffffff;
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}
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return (this.twister.int32() >>> 0) % limit;
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},
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float: function () {
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// Returns a float in [0, 1]. Uniform distribution.
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return this.twister.real2() >>> 0;
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},
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range: function (start, limit) {
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// Returns an integer in [start, limit]. Uniform distribution.
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if (isNaN(start) || isNaN(limit)) {
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Utils.traceback();
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throw new TypeError("random.range() received a non number type: '" + start + "', '" + limit + "')");
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}
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return random.number(limit - start + 1) + start;
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},
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ludOneTo: function(limit) {
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// Returns a float in [1, limit]. The logarithm has uniform distribution.
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return Math.exp(random.float() * Math.log(limit));
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},
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item: function (list) {
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if (!(list instanceof Array || (typeof list != "string" && "length" in list))) {
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Utils.traceback();
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throw new TypeError("random.item() received a non array type: '" + list + "'");
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}
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return list[this.number(list.length)];
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},
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key: function (obj) {
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let list = [];
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for (let i in obj) {
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list.push(i);
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}
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return this.item(list);
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},
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bool: function () {
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return this.item([true, false]);
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},
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pick: function (obj) {
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if (typeof obj == "function") {
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return obj();
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}
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if (obj instanceof Array) {
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return this.pick(this.item(obj));
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}
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return obj;
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},
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chance: function (limit) {
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if (limit == null || limit === undefined) {
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limit = 2;
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}
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if (isNaN(limit)) {
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Utils.traceback();
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throw new TypeError("random.chance() received a non number type: '" + limit + "'");
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}
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return this.number(limit) == 1;
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},
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choose: function (list, flat) {
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if (!(list instanceof Array)) {
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Utils.traceback();
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throw new TypeError("random.choose() received a non-array type: '" + list + "'");
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}
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let total = 0;
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for (let i = 0; i < list.length; i++) {
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total += list[i][0];
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}
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let n = this.number(total);
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for (let i = 0; i < list.length; i++) {
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if (n < list[i][0]) {
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if (flat == true) {
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return list[i][1];
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} else {
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return this.pick([list[i][1]]);
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}
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}
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n = n - list[i][0];
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}
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if (flat == true) {
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return list[0][1];
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}
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return this.pick([list[0][1]]);
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},
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weighted: function (wa) {
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// More memory-hungry but hopefully faster than random.choose$flat
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let a = [];
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for (let i = 0; i < wa.length; ++i) {
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for (let j = 0; j < wa[i].w; ++j) {
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a.push(wa[i].v);
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}
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}
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return a;
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},
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use: function (obj) {
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return random.bool() ? obj : "";
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},
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shuffle: function (arr) {
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let len = arr.length;
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let i = len;
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while (i--) {
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let p = random.number(i + 1);
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let t = arr[i];
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arr[i] = arr[p];
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arr[p] = t;
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}
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},
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shuffled: function (arr) {
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let newArray = arr.slice();
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random.shuffle(newArray);
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return newArray;
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},
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subset: function (list, limit) {
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if (!(list instanceof Array)) {
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Utils.traceback();
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throw new TypeError("random.some() received a non-array type: '" + list + "'");
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}
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if (typeof limit == 'number') {
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limit = this.range(0, list.length);
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}
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let result = [];
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for (let i = 0; i < limit; i++) {
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result.push(this.pick(list));
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}
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return result;
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}
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};
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