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markov.js
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markov.js
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import { parse, stringify } from 'flatted';
/*
* See full set of options for RiMarkov (https://rednoise.org/rita/reference/RiTa/markov/index.html)
* and RiMarkov.generate (https://rednoise.org/rita/reference/RiMarkov/generate/index.html)
*/
class RiMarkov {
constructor(n, opts = {}) {
this.n = n;
this.root = new Node(null, 'ROOT');
this.trace = opts.trace;
this.mlm = opts.maxLengthMatch;
this.maxAttempts = opts.maxAttempts || 999;
this.tokenize = opts.tokenize || RiTa().tokenize;
this.untokenize = opts.untokenize || RiTa().untokenize;
this.disableInputChecks = opts.disableInputChecks;
this.sentenceStarts = []; // allow duplicates for prob
this.sentenceEnds = new Set(); // no duplicates
if (this.n < 2) throw Error('minimum N is 2');
if (this.mlm && this.mlm < this.n) throw Error('maxLengthMatch must be >= N');
// we store inputs to verify we don't duplicate sentences
if (!this.disableInputChecks || this.mlm) this.input = [];
// add text if supplied as opt //
if (opts.text) this.addText(opts.text);
}
addText(text, multiplier = 1) {
let sents = Array.isArray(text) ? text : RiTa().sentences(text);
// add new tokens for each sentence start/end
let wrap, allWords = [];
for (let k = 0; k < multiplier; k++) {
for (let i = 0; i < sents.length; i++) {
let words = this.tokenize(sents[i]);
this.sentenceStarts.push(words[0]);
this.sentenceEnds.add(words[words.length - 1]);
allWords.push(...words);
}
this.treeify(allWords);
}
if (!this.disableInputChecks || this.mlm) {
for (let i = 0; i < allWords.length; i++) {
this.input.push(allWords[i]);
}
}
}
generate(count, opts = {}) {
if (arguments.length === 1 && typeof count === 'object') {
opts = count;
count = 1;
}
const num = count || 1;
const minLength = opts.minLength || 5;
const maxLength = opts.maxLength || 35;
if (typeof opts.temperature !== 'undefined' && opts.temperature <= 0) {
throw Error("Temperature option must be greater than 0");
}
let tries = 0, tokens = [], usedStarts = [];
let minIdx = 0, sentenceIdxs = [];
let markedNodes = [];
////////////////////////// local functions /////////////////////////////
const unmarkNodes = () => {
markedNodes.forEach(n => n.marked = false);
}
const resultCount = () => {
return tokens.filter(t => this._isEnd(t)).length;
}
const markNode = (node) => {
if (node) {
// save current tokens as a sort of hash of current state
node.marked = tokens.reduce((acc, e) => acc + e.token, '');
markedNodes.push(node);
}
}
const notMarked = (cn) => {
let tmap = tokens.reduce((acc, e) => acc + e.token, '');
return cn.marked !== tmap;
}
const validateSentence = (next) => {
markNode(next);
let sentIdx = sentenceIdx();
if (this.trace) console.log(1 + (tokens.length - sentIdx),
next.token, '[' + next.parent.childNodes().filter
(t => t !== next).map(t => t.token) + ']'); // print each child
let sentence = tokens.slice(sentIdx).map(t => t.token);
sentence.push(next.token);
if (sentence.length < minLength) {
fail('too-short (pop: ' + next.token + ')');
//console.log('pop: ' + next.token);
return false;
}
if (!this.disableInputChecks && isSubArray(sentence, this.input)) {
fail('in-input (pop: ' + next.token + ')');
return false;
}
let flatSent = this.untokenize(sentence);
if (!opts.allowDuplicates && isSubArray(sentence, tokens.slice(0, sentIdx))) {
fail('duplicate (pop: ' + next.token + ')');
return false;
}
tokens.push(next);
sentenceIdxs.push(tokens.length);
if (this.trace) console.log('OK (' + resultCount() + '/' + num + ') "' +
flatSent + '" sidxs=[' + sentenceIdxs + ']\n');
return true;
}
const fail = (msg, sentence, forceBacktrack) => {
tries++;
let sentIdx = sentenceIdx();
sentence = sentence || this._flatten(tokens.slice(sentIdx));
if (tries >= this.maxAttempts) throwError(tries, resultCount());
//if (tokens.length >= this.maxAttempts) throwError(tries, resultCount()); // ???
let parent = this._pathTo(tokens);
let numChildren = parent ? parent.childNodes({ filter: notMarked }).length : 0;
if (this.trace) console.log('Fail:', msg, '\n -> "' + sentence + '" ',
tries + ' tries, ' + resultCount() + ' successes, numChildren=' + numChildren
+ (forceBacktrack ? ' forceBacktrack*' : (' parent="' + parent.token
+ '" goodKids=[' + parent.childNodes({ filter: notMarked }).map(t => t.token) + ']'
+ '" allKids=[' + parent.childNodes().map(t => t.token) + ']')));
if (forceBacktrack || numChildren === 0) {
backtrack();
}
}
// step back until we have a parent with children
// or we have reached our start
// if we find an option, return true
const backtrack = () => {
let parent, tc;
for (let i = 0; i < 99; i++) { // tmp-remove?
let last = tokens.pop();
markNode(last);
if (this._isEnd(last)) sentenceIdxs.pop();
let sentIdx = sentenceIdx();
let backtrackUntil = Math.max(sentIdx, minIdx);
if (this.trace) console.log('backtrack#' + tokens.length,
'pop "' + last.token + '" ' + (tokens.length - sentIdx)
+ "/" + backtrackUntil + ' ' + this._flatten(tokens));
parent = this._pathTo(tokens);
tc = parent.childNodes({ filter: notMarked });
if (tokens.length <= backtrackUntil) {
if (minIdx > 0) { // have seed
if (tokens.length <= minIdx) { // back at seed
if (!tc.length) throw Error('back at barren-seed1: case 0');
if (this.trace) console.log('case 1');
return true;
}
else { // back at sentence-start with seed
if (!tc.length) {
if (this.trace) console.log('case 2: back at SENT-START: "'
+ this._flatten(tokens) + '" sentenceIdxs=' + sentenceIdxs
+ ' ok=[' + parent.childNodes({ filter: notMarked }).map(t => t.token)
+ '] all=[' + parent.childNodes().map(t => t.token) + ']');
sentenceIdxs.pop();
}
else { // continue
if (this.trace) console.log('case 3');
}
}
}
else { // TODO: recheck
if (this.trace) console.log('case 4: back at start of sentence'
+ ' or 0: ' + tokens.length, sentenceIdxs);
if (!tokens.length) {
sentenceIdxs = [];
return selectStart();
}
}
return true;
}
if (tc.length) {
sentIdx = sentenceIdx();
if (this.trace) console.log((tokens.length - sentIdx)
+ ' ' + this._flatten(tokens) + '\n ok=['
+ tc.map(t => t.token) + '] all=[' + parent.childNodes
({ filter: notMarked }).map(t => t.token) + ']');
return parent;
}
}
throw Error('Invalid state in backtrack() ['
+ tokens.map(t => t.token) + ']');
}
const sentenceIdx = () => {
let len = sentenceIdxs.length;
return len ? sentenceIdxs[len - 1] : 0;
}
const selectStart = () => {
let seed = opts.seed;
if (seed && seed.length) {
if (typeof seed === 'string') seed = this.tokenize(seed);
let node = this._pathTo(seed, this.root);
while (!node.isRoot()) {
tokens.unshift(node);
node = node.parent;
}
}
// we need a new sentence-start
else if (!tokens.length || this._isEnd(tokens[tokens.length - 1])) {
let usableStarts = this.sentenceStarts.filter(ss => notMarked(this.root.child(ss)));
if (!usableStarts.length) throw Error('No valid sentence-starts remaining');
let start = RiTa().random(usableStarts);
let startTok = this.root.child(start);
markNode(startTok);
usableStarts = this.sentenceStarts.filter(ss => notMarked(this.root.child(ss)));
tokens.push(startTok);
}
else {
throw Error('Invalid call to selectStart: ' + this._flatten(tokens));
}
}
////////////////////////////////// code ////////////////////////////////////////
selectStart();
while (resultCount() < num) {
let sentIdx = sentenceIdx();
if (tokens.length - sentIdx >= maxLength) {
fail('too-long', 0, true);
continue;
}
let parent = this._pathTo(tokens);
let next = this._selectNext(parent, opts.temperature, tokens, notMarked);
if (!next) { // no valid children, pop and continue;
fail('mlm-fail(' + this.mlm + ')', this._flatten(tokens), true);
continue;
}
if (this._isEnd(next)) {
validateSentence(next);
continue;
}
tokens.push(next);
if (this.trace) console.log(tokens.length - sentIdx, next.token,
'[' + parent.childNodes({ filter: notMarked }) // print unmarked kids
.filter(t => t !== next).map(t => t.token) + ']');
}
unmarkNodes();
let str = this.untokenize(tokens.map(t => t.token)).trim();
return num > 1 ? this._splitEnds(str) : str;
}
toJSON() {
let data = Object.keys(this).reduce
((acc, k) => Object.assign(acc, { [k]: this[k] }), {});
data.sentenceEnds = [...data.sentenceEnds]; // set -> []
return stringify(data);
}
static fromJSON(json) {
// parse the json and merge with new object
let parsed = parse(json);
let rm = Object.assign(new RiMarkov(), parsed);
// convert our json array back to a set
rm.sentenceEnds = new Set(...parsed.sentenceEnds);
// handle json converting undefined [] to empty []
if (!parsed.input) rm.input = undefined;
// then recreate the n-gram tree with Node objects
let jsonRoot = rm.root;
populate(rm.root = new Node(null, 'ROOT'), jsonRoot);
return rm;
}
/* returns array of possible tokens after pre and (optionally) before post */
completions(pre, post) {
let tn, result = [];
if (post) { // fill the center
if (pre.length + post.length > this.n) throw Error
('Sum of pre.length && post.length must be <= N, was ' + (pre.length + post.length));
if (!(tn = this._pathTo(pre))) {
if (!RiTa().SILENT) console.warn('Unable to find nodes in pre: ' + pre);
return;
}
const nexts = tn.childNodes();
for (let i = 0; i < nexts.length; i++) {
let atest = pre.slice(0);
atest.push(nexts[i].token, ...post);
if (this._pathTo(atest)) result.push(nexts[i].token);
}
} else { // fill the end
const pr = this.probabilities(pre);
result = Object.keys(pr).sort((a, b) => pr[b] - pr[a]);
}
return result;
}
/* return an object mapping {string -> prob} */
probabilities(path, temp) {
if (!Array.isArray(path)) path = this.tokenize(path);
const probs = {};
const parent = this._pathTo(path);
if (parent) {
const children = parent.childNodes();
const weights = children.map(n => n.count);
const pdist = RiMarkov.parent.randomizer.ndist(weights, temp);
children.forEach((c, i) => probs[c.token] = pdist[i]);
}
return probs;
}
probability(data) {
let p = 0;
if (data && data.length) {
let tn = (typeof data === 'string') ?
this.root.child(data) : this._pathTo(data);
if (tn) p = tn.nodeProb(true); // no meta
}
return p;
}
toString(root, sort) {
root = root || this.root;
return root.asTree(sort).replace(/{}/g, '');
}
size() {
return this.root.childCount(true);
}
////////////////////////////// end API ////////////////////////////////
// selects child based on temp, filter and probability (throws)
_selectNext(parent, temp, tokens, filter) {
if (!parent) throw Error('no parent:' + this._flatten(tokens));
let children = parent.childNodes({ filter });
if (!children.length) {
if (this.trace) console.log('No children to select, parent=' + parent.token
+ ' children=ok[], all=[' + parent.childNodes().map(t => t.token) + ']');
return;
}
// basic case: just prob. select from children
if (!this.mlm || this.mlm > tokens.length) {
return parent.pselect(filter);
}
const validateMlms = (word, nodes) => {
let check = nodes.slice(-this.mlm).map(n => n.token);
check.push(word.token);
return !isSubArray(check, this.input);
}
const rand = RiMarkov.parent.randomizer;
const weights = children.map(n => n.count);
const pdist = rand.ndist(weights, temp);
const tries = children.length * 2;
const selector = rand.random();
// loop 2x here as we may skip earlier nodes
// but keep track of tries to avoid duplicates
const tried = [];
for (let i = 0, pTotal = 0; i < tries; i++) {
let idx = i % children.length;
pTotal += pdist[idx];
let next = children[idx];
if (selector < pTotal) {
if (!tried.includes(next.token)) {
tried.push(next.token);
return validateMlms(next, tokens) ? next : false;
}
}
}
}
/*
* Returns true if node (or string) is a sentence end
*/
_isEnd(node) {
if (node) {
let check = node;
if ('token' in node) check = node.token; // needed?
return this.sentenceEnds.has(check);
}
return false;
}
/*
* Follows 'path' (using only the last n-1 tokens) from root and returns
* the node for the last element if it exists, otherwise undefined
* @param {Node[]} path
* @param {node} root of tree to search
* @return {node} or undefined
*/
_pathTo(path, root) {
root = root || this.root;
if (typeof path === 'string') path = [path];
if (!path || !path.length || this.n < 2) return root;
let idx = Math.max(0, path.length - (this.n - 1));
let node = root.child(path[idx++]);
for (let i = idx; i < path.length; i++) {
if (node) node = node.child(path[i]);
}
return node; // can be undefined
}
/* add tokens to tree */
treeify(tokens) {
let root = this.root;
for (let i = 0; i < tokens.length; i++) {
let node = root;
let words = tokens.slice(i, i + this.n);
let wrap = 0;
for (let j = 0; j < this.n; j++) {
let hidden = false;
if (j >= words.length) {
words[j] = tokens[wrap++];
hidden = true;
}
node = node.addChild(words[j]);
if (hidden) node.hidden = true;
}
}
}
/*
* Split string of sentences on sentence-ends, keeping delims
* hack: there _must_ be a better way to do thisn
*/
_splitEnds(str) {
let se = [...this.sentenceEnds];
let re = '(' + se.reduce((acc, w) => acc + w + '|', '')
.slice(0, -1).replace(/[.*+?^${}()[\]\\]/g, '\\$&') + ")";
let arr = [], parts = str.split(new RegExp(re, 'g'));
for (let i = 0; i < parts.length; i++) {
if (!parts[i].length) continue;
if ((i % 2) === 0) {
arr.push(parts[i]);
}
else {
arr[arr.length - 1] += parts[i];
}
}
return arr.map(a => a.trim());
}
/* create a sentence string from an array of nodes */
_flatten(nodes) {
if (!nodes || (Array.isArray(nodes) && !nodes.length)) return '';
if (nodes.token) return nodes.token; // single-node
let arr = nodes.map(n => n ? n.token : '[undef]');
let sent = this.untokenize(arr);
return sent.replace(MULTI_SP_RE, ' ');
}
}
class Node {
constructor(parent, word, count) {
this.children = {};
this.parent = parent;
this.token = word;
this.count = count || 0;
this.numChildren = -1; // for cache
this.marked = false;
}
// Find a (direct) child node with matching token, given a word or node
child(word) {
let lookup = word;
if (word.token) lookup = word.token;
return this.children[lookup];
}
pselect(filter) {
const rand = RiMarkov.parent.randomizer;
const children = this.childNodes({ filter });
if (!children.length) {
throw Error('No eligible child for "' + this.token
+ "\" children=[" + this.childNodes().map(t => t.token) + "]");
}
const weights = children.map(n => n.count);
const pdist = rand.ndist(weights);
const idx = rand.pselect(pdist);
return children[idx];
}
isLeaf(ignoreHidden) { return this.childCount(ignoreHidden) < 1; }
isRoot() { return !this.parent; }
childNodes(opts) {
let sort = opts && opts.sort;
let filter = opts && opts.filter;
let kids = Object.values(this.children);
if (filter) kids = kids.filter(filter);
if (sort) kids.sort((a, b) => b.count !== a.count
? b.count - a.count
: b.token.localeCompare(a.token));
return kids;
}
childCount(ignoreHidden) {
if (this.numChildren === -1) {
let opts = {};
if (ignoreHidden) opts.filter = (t => !t.hidden);
this.numChildren = this.childNodes(opts)
.reduce((a, c) => a + c.count, 0);
}
return this.numChildren;
}
nodeProb(excludeMetaTags) {
if (!this.parent) throw Error('no parent');
return this.count / this.parent.childCount(excludeMetaTags);
}
// Increments count for a child node and returns it
addChild(word, count) {
this.numChildren = -1; // invalidate cache
count = count || 1;
let node = this.children[word];
if (!node) {
node = new Node(this, word);
this.children[word] = node;
}
node.count += count;
return node;
}
toString() {
return this.parent ? '\'' + this.token + '\' [' + this.count
+ ',p=' + this.nodeProb().toFixed(3) + ']' : 'Root'
}
asTree(sort, showHiddenNodes) {
let s = this.token + ' ';
if (this.parent) s += '(' + this.count + ')->';
s += '{';
return this.childCount(true) ? stringulate(this, s, 1, sort, !showHiddenNodes) : s + '}';
}
}
// --------------------------------------------------------------
function stringulate(mn, str, depth, sort, ignoreHidden) {
sort = sort || false;
let indent = '\n';
let l = mn.childNodes({ sort: true, filter: t => !t.hidden });
if (!l.length) return str;
for (let j = 0; j < depth; j++) indent += " ";
for (let i = 0; i < l.length; i++) {
let node = l[i];
if (node && node.token) {
str += indent + "'" + encode(node.token) + "'";
if (!node.isRoot()) str += " [" + node.count
+ ",p=" + node.nodeProb().toFixed(3) + "]";
if (!node.isLeaf(ignoreHidden)) {
//console.log('appending "{" for '+node.token, node.childNodes());
str += ' {';
}
str = mn.childCount(ignoreHidden) ? stringulate(node, str, depth + 1, sort) : str + '}';
}
}
indent = '\n';
for (let j = 0; j < depth - 1; j++) indent += " ";
return str + indent + "}";
}
function encode(tok) {
if (tok === '\n') tok = '\\n';
if (tok === '\r') tok = '\\r';
if (tok === '\t') tok = '\\t';
if (tok === '\r\n') tok = '\\r\\n';
return tok;
}
function populate(objNode, jsonNode) {
if (!jsonNode) return;
let children = Object.values(jsonNode.children);
for (let i = 0; i < children.length; i++) {
let child = children[i];
let newNode = objNode.addChild(child.token, child.count);
populate(newNode, child); // recurse
}
}
function RiTa() { return RiMarkov.parent; }
function throwError(tries, oks) {
throw Error('Failed after ' + tries + ' tries'
+ (oks ? ' and ' + oks + ' successes' : '')
+ ', you may need to adjust options or add more text');
}
function isSubArray(find, arr) {
if (!arr || !arr.length) return false;
OUT: for (let i = find.length - 1; i < arr.length; i++) {
for (let j = 0; j < find.length; j++) {
if (find[find.length - j - 1] !== arr[i - j]) continue OUT;
if (j === find.length - 1) return true;
}
}
return false;
}
const MULTI_SP_RE = / +/g;
export default RiMarkov;