markov-strings-db

A rewrite of scambier/markov-strings made to utilize a relational SQL database rather than an in-memory object. The goal is to reduce memory usage, disk reads/writes, remove batch corpus generation, and increase performance.

This should be mostly functionally compatible with markov-strings v3, however the API usage varies. This version supports importing data exports from markov-strings v3 for easy migration.

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A simplistic Markov chain text generator. Give it an array of strings, and it will output a randomly generated string.

This rewrite was created for the Discord bot markov-discord.

Prerequisites

• NodeJS 14+
• The host app must be configured with a TypeORM-compatible database driver

Installing

• npm i markov-strings-db
• Setup a database driver (this project was tested with better-sqlite3)
  • Step 4 from this guide
• Setup a data source config

Usage

import Markov from 'markov-strings-db';
import ormconfig from './ormconfig';
import { DataSource } from 'typeorm';

const data = [/* insert a few hundreds/thousands sentences here */];


// Instantiate the Markov generator
const markov = new Markov({ options: { stateSize: 2 }});

// If you have your own database you'd like to combine with Markov's, make sure to extend your data source options
const dataSourceOptions = await Markov.extendDataSourceOptions(ormconfig);
// Required: create a data source before using a markov instance. You only need to do this once.
const dataSource = new DataSource(dataSourceOptions);
await dataSource.initialize();

// If you have a non-default data source (you probably don't), pass it in here. Otherwise, setup() is called implicitly on any async function.
await markov.setup(dataSource);

// Add data for the generator
await markov.addData(data)

const generateOptions = {
  maxTries: 20, // Give up if I don't have a sentence after 20 tries (default is 10)

  // You may need to manually filter raw results to get something that fits your needs.
  filter: (result) => {
    return result.string.split(' ').length >= 5 && // At least 5 words
      result.string.endsWith('.')                  // End sentences with a dot.
  }
}

// Generate a sentence
const result = await markov.generate(generateOptions)
console.log(result)
/*
  {
    string: 'lorem ipsum dolor sit amet etc.',
    score: 42,
    tries: 5,
    refs: [ an array of objects ]
  }
*/

await markov.destroy();

API

Each function is documented via JSDoc and its types. Hover over a function in your IDE for details on it.