A simple Perceptron in Scala

perceptron.scala

import java.util.Random

class Perceptron(weights: Array[Double], learningRate: Double = 0.01, bias: Double = 1.0) {
  def fit(input: Array[Array[Double]], labels: Array[Double]): Array[Double] =
    fitWithBias(input, labels)

  def fitWithBias(data: Array[Array[Double]], labels: Array[Double], epochs: Int = 1000): Array[Double] =
    train(addBias(data), labels, epochs)

  def train(data: Array[Array[Double]], labels: Array[Double], epochs: Int): Array[Double] =
    (0 until epochs).foldLeft(weights)((w, _) => trainIteration(w, data, labels))

  def trainIteration(weights: Array[Double], data: Array[Array[Double]], labels: Array[Double]): Array[Double] =
    data.zip(labels).foldLeft(weights)((w, p) => p match {
      case (input, label) =>
        val p = activate(dotProduct(input, weights))
        val err = label - p
        val updatedWeights = input.map(i => i * learningRate * err)
        w.zip(updatedWeights).map(p => p._1 + p._2)
    })

  def activate(x: Double): Double =
    if (x >= 0) 1 else 0

  def dotProduct(v1: Array[Double], v2: Array[Double]): Double =
    v1.zip(v2).map(p => p._1 * p._2).sum

  def addBias(data: Array[Array[Double]]): Array[Array[Double]] =
    data.map(arr => addRowBias(arr))

  def addRowBias(input: Array[Double]): Array[Double] =
    input :+ bias

  def predict(weights: Array[Double], input: Array[Double]): Double =
    activate(dotProduct(weights, addRowBias(input)))
}

val rnd = new Random()

def randomWeights(n: Int): Array[Double] =
  (0 until n).map(_ => rnd.nextDouble(0, 1)).toArray

val input: Array[Array[Double]] = Array(Array(1, 0), Array(1, 1), Array(0, 1), Array(0, 0))
val labels: Array[Double] = Array(0, 1, 0, 0) // AND
//val labels: Array[Double] = Array(1, 1, 1, 0) // OR
//val labels: Array[Double] = Array(1, 0, 1, 0) // XOR
val weights = randomWeights(3)
val p = new Perceptron(weights)
val ws = p.fit(input, labels)
p.predict(ws, Array(0, 1))
p.predict(ws, Array(1, 1))
p.predict(ws, Array(1, 0))
p.predict(ws, Array(0, 0))