random-forest

Random forest method. Ported to JavaScript with WebAssembly. Async computation and multithreading implemented with WebWorkers (for browsers). No tests yet. See examples in the example folder.

• Fast
• Sync/async modes
• Threads support
• CommonJS module

Install

npm install -S random-forest

Sync mode

Init

const { RandomForestClassifier, RandomForestRegressor } = require('random-forest')
 
const rf = new RandomForestClassifier({
  nEstimators: 100,
  maxDepth: 10,
  maxFeatures: 'auto',
  minSamplesLeaf: 5,
  minInfoGain: 0,
})

Training, Predicting

rf.train(Xtrain, ytrain)
const ypred = rf.predict(Xtest)

Saving, Loading models

const model = rf.save()
fs.writeFileSync('example.model', model)
const modelLoaded = new Uint8Array(fs.readFileSync('example.model'))
rf.load(modelLoaded)
const ypred = rf.predict(Xtest)

Some browsers doesn't allow running WebAssembly in a sync mode. In such case, you can try async mode described below.

Async mode

const { RandomForestClassifier, RandomForestRegressor } = require('random-forest/async')
 
// ! Don't miss /async part in require('random-forest/async') !
 
;(async function f () {
  const rf = new RandomForestClassifier({
    nEstimators: 100,
    maxDepth: 10,
    maxFeatures: 'auto',
    minSamplesLeaf: 5,
    minInfoGain: 0,
    nJobs: 4 // Control the number of threads (workers) with this param
  })
  await rf.init()
  await rf.train(Xtrain, ytrain)
  const ypred = await rf.predict(Xtest)
  console.log(ypred, ytest)
})()

Currently the async mode doesn't support loading/saving models.

Development

Contributions are very welcomed. Some insights on how everything works:

Building steps:

1. The native code is loaded from the native-forest repo, a fork from RandomForests, a C++ implementation of random forests
2. Custom C++ interfaces are in src/api.cpp and src/api.h.
3. Emscripten compiles the native-forest code with defined interfaces into native/native.js and native/native.wasm. Compilation settings located in Makefile
4. To load WebAssembly in sync mode, prepare-wasm.js script converts the wasm file into a Uint8 array and stores it in the wrappers folder
5. Then src/base.js loads wrapper/native.bin.js as a regular CommonJS module, initializes it using the native/native.js module utils and then inititalizes native functions with cwrap
6. That's all what needed for the sync mode to work. Now prepare async version. To make it easier loading and bundling the module, a WebWorker script is bundled, rather than uses importScript. It's also loaded not as a separate file, but Blob. To generate the Blob we need the worker to be compiled first, then loaded as a string
7. Bundle src/worker.js into dist/worker.js
8. Use prepare-worker.js to read code of dist/worker.js and save it as a module in wrapper/worker.code.js
9. Load wrapped code in src/async.js, init Blob, the URL, and WebWorkers
10. In async mode results are aggregates