Created
February 22, 2019 10:27
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'use strict'; | |
class Markov { | |
constructor() { | |
this.minLength = 6; | |
this.maxLength = 30; | |
this.dict = {}; | |
} | |
addSentence(text) { | |
// '\0' is a sentinel marking the beginning + end of sentences | |
text = "\0 \0 " + text + " \0"; | |
let words = text.match(/\S+\s*/g).map(function(x) { return x.trim(); }); | |
for (let i = 2; i < text.length; i++) { | |
let k = words[i-2] + ' ' + words[i-1]; | |
if (!this.dict[k]) | |
this.dict[k] = []; | |
this.dict[k].push(words[i]); | |
} | |
} | |
getRandomValue(key) { | |
if (!this.dict[key]) { | |
console.log("error: encountered a state we can't proceed from: " + key); | |
return '\0'; | |
} | |
return this.dict[key][Math.floor(Math.random() * this.dict[key].length)]; | |
} | |
generateSentence(seedword) { | |
// try up to 100 times to generate a sentence that is less than maxLength | |
for (let i = 0; i < 100; i++) { | |
let sentence = ['\0', '\0']; | |
if (seedword) { | |
let words = seedword.match(/\S+\s*/g).map(function(x) { return x.trim(); }); | |
sentence = sentence.concat(words); | |
let search = sentence.slice(-2).join(' '); | |
if (!this.dict[search]) { | |
return "Can't work with " + seedword + " m9"; | |
} | |
} | |
while (1) { | |
let search = sentence.slice(-2).join(' '); | |
let found = this.getRandomValue(search); | |
if (found == '\0') | |
break; | |
sentence.push(found); | |
if (sentence.length > this.maxLength+2) { | |
sentence.pop(); | |
break; | |
} | |
} | |
if (i == 99 || (sentence.length < this.maxLength+2 && sentence.length >= this.minLength+2)) { | |
sentence.shift(); sentence.shift(); | |
return sentence.join(' '); | |
} | |
} | |
} | |
generate(sentenceCount) { | |
let sentences = []; | |
while (sentenceCount--) { | |
sentences.push(this.generateSentence()); | |
} | |
return sentences.join(' '); | |
} | |
} | |
module.exports = Markov; |
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