Perceptron: Difference between revisions

=={{header|Kotlin}}==

{{trans|Java}}

<lang scala>// version 1.1.4-3

import java.awt.*

import java.awt.event.ActionEvent

import java.util.Random

import javax.swing.JPanel

import javax.swing.JFrame

import javax.swing.Timer

import javax.swing.SwingUtilities

class Perceptron(n: Int) : JPanel() {

class Trainer(x: Double, y: Double, val answer: Int) {

val inputs = doubleArrayOf(x, y, 1.0)

}

val weights: DoubleArray

val training: Array<Trainer>

val c = 0.00001

var count = 0

init {

val r = Random()

val dim = Dimension(640, 360)

preferredSize = dim

background = Color.white

weights = DoubleArray(n) { r.nextDouble() * 2.0 - 1.0 }

training = Array(2000) {

val x = r.nextDouble() * dim.width

val y = r.nextDouble() * dim.height

val answer = if (y < f(x)) -1 else 1

Trainer(x, y, answer)

}

Timer(10) { repaint() }.start()

}

private fun f(x: Double) = x * 0.7 + 40.0

fun feedForward(inputs: DoubleArray): Int {

if (inputs.size != weights.size)

throw IllegalArgumentException("Weights and input length mismatch")

val sum = weights.zip(inputs) { w, i -> w * i }.sum()

return activate(sum)

}

fun activate(s: Double) = if (s > 0.0) 1 else -1

fun train(inputs: DoubleArray, desired: Int) {

val guess = feedForward(inputs)

val error = desired - guess

for (i in 0 until weights.size) weights[i] += c * error * inputs[i]

}

public override fun paintComponent(gg: Graphics) {

super.paintComponent(gg)

val g = gg as Graphics2D

g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

RenderingHints.VALUE_ANTIALIAS_ON)

// we're drawing upside down

var x = width

var y = f(x.toDouble()).toInt()

g.stroke = BasicStroke(2.0f)

g.color = Color.orange

g.drawLine(0, f(0.0).toInt(), x, y)

train(training[count].inputs, training[count].answer)

count = (count + 1) % training.size

g.stroke = BasicStroke(1.0f)

g.color = Color.black

for (i in 0 until count) {

val guess = feedForward(training[i].inputs)

x = training[i].inputs[0].toInt() - 4

y = training[i].inputs[1].toInt() - 4

if (guess > 0) g.drawOval(x, y, 8, 8)

else g.fillOval(x, y, 8, 8)

}

}

}

fun main(args: Array<String>) {

SwingUtilities.invokeLater {

val f = JFrame()

with(f) {

defaultCloseOperation = JFrame.EXIT_ON_CLOSE

title = "Perceptron"

isResizable = false

add(Perceptron(3), BorderLayout.CENTER)

pack()

setLocationRelativeTo(null)

isVisible = true

}

}

}</lang>