Add TrainingDataGenerator

java/src/org/futo/inputmethod/latin/xlm/TrainingDataGenerator.kt

+package org.futo.inputmethod.latin.xlm
+
+import kotlin.math.PI
+import kotlin.math.ceil
+import kotlin.math.cos
+import kotlin.math.ln
+import kotlin.math.pow
+import kotlin.math.sqrt
+import kotlin.random.Random
+import kotlin.random.nextInt
+
+class Vector2(val x: Float, val y: Float) {
+    operator fun plus(other: Vector2): Vector2 {
+        return Vector2(x + other.x, y + other.y)
+    }
+
+    operator fun minus(other: Vector2): Vector2 {
+        return Vector2(x - other.x, y - other.y)
+    }
+
+    fun magnitudeSquared(): Float {
+        return (x * x) + (y * y)
+    }
+}
+
+fun randomNormal(mean: Float, standardDeviation: Float): Float {
+    val u1 = Random.nextFloat()
+    val u2 = Random.nextFloat()
+
+    val randStdNormal = sqrt(-2.0 * ln(u1.toDouble())) * cos(2.0 * PI * u2.toDouble())
+
+    return (mean + standardDeviation * randStdNormal).toFloat()
+}
+
+private interface KeyboardLayout {
+    val tapSize: Vector2
+
+    fun getKeyPosition(character: Char): Vector2?
+    fun getClosestKey(position: Vector2): Char
+}
+
+const val SHIFT_KEY = '\u000f'
+const val BACKSPACE_KEY = '\u0008'
+object QWERTYKeyboardLayout : KeyboardLayout {
+    override val tapSize: Vector2 = Vector2(80.0f, 80.0f)
+
+    // Rough QWERTY positions based on eyeballing it
+    private val KEYBOARD_KEYS = hashMapOf(
+        'q' to Vector2(75.0f, 106.0f),
+        'w' to Vector2(214.0f, 106.0f),
+        'e' to Vector2(363.0f, 106.0f),
+        'r' to Vector2(499.0f, 106.0f),
+        't' to Vector2(645.0f, 106.0f),
+        'y' to Vector2(789.0f, 106.0f),
+        'u' to Vector2(928.0f, 106.0f),
+        'i' to Vector2(1073.0f, 106.0f),
+        'o' to Vector2(1216.0f, 106.0f),
+        'p' to Vector2(1357.0f, 106.0f),
+        'a' to Vector2(150.0f, 312.0f),
+        's' to Vector2(291.0f, 312.0f),
+        'd' to Vector2(434.0f, 312.0f),
+        'f' to Vector2(574.0f, 312.0f),
+        'g' to Vector2(717.0f, 312.0f),
+        'h' to Vector2(859.0f, 312.0f),
+        'j' to Vector2(1005.0f, 312.0f),
+        'k' to Vector2(1140.0f, 312.0f),
+        'l' to Vector2(1288.0f, 312.0f),
+        SHIFT_KEY to Vector2(113.0f, 515.0f),
+        'z' to Vector2(287.0f, 515.0f),
+        'x' to Vector2(434.0f, 515.0f),
+        'c' to Vector2(576.0f, 515.0f),
+        'v' to Vector2(718.0f, 515.0f),
+        'b' to Vector2(860.0f, 515.0f),
+        'n' to Vector2(1003.0f, 515.0f),
+        'm' to Vector2(1145.0f, 515.0f),
+        BACKSPACE_KEY to Vector2(1329.0f, 515.0f),
+    )
+
+    override fun getKeyPosition(character: Char): Vector2? {
+        return KEYBOARD_KEYS[character]
+    }
+
+    override fun getClosestKey(position: Vector2): Char {
+        return KEYBOARD_KEYS.minBy {
+            (it.value - position).magnitudeSquared()
+        }.key
+    }
+
+}
+
+private object WordMisspelling {
+    fun substituteKeyboardLetters(layout: KeyboardLayout, word: String, temperature: Float = 0.6f): String {
+        val keys = word.lowercase().toList()
+        val newKeys = mutableListOf<Char>()
+
+        keys.forEach { char ->
+            val position = layout.getKeyPosition(char) ?: return@forEach
+
+            val newPosition = Vector2(
+                randomNormal(position.x, temperature * layout.tapSize.x),
+                randomNormal(position.y, temperature * layout.tapSize.y)
+            )
+
+            val newKey = layout.getClosestKey(newPosition)
+
+            if(newKey == SHIFT_KEY) {
+                // next char should be uppercased, but it currently doesn't matter
+            }else if(newKey == BACKSPACE_KEY) {
+                if(newKeys.size > 0) newKeys.removeLast()
+            }else {
+                newKeys.add(newKey)
+            }
+        }
+
+        return String(newKeys.toCharArray())
+    }
+
+    fun misspellWord(word: String, correctness: Float = 0.8f): String {
+        var misspelledWord = word.trim().lowercase().replace("'", "")
+
+        val getRand = { Random.nextFloat().pow(correctness) }
+
+        // TODO: Random word transformations - substituting letters, deleting, repeating, adding, transposing
+
+        // Substitute the word's characters with nearby ones randomly
+        misspelledWord = substituteKeyboardLetters(QWERTYKeyboardLayout, misspelledWord, temperature = 1.0f * getRand())
+
+        // Trim word randomly as if the user hasn't finished writing the word yet
+        // This helps the model learn to complete partially-written words
+        if((getRand() > 0.33) && (misspelledWord.length >= 2)) {
+            val newLength = ceil((1.0 - (getRand() * getRand())) * misspelledWord.length).toInt().coerceAtLeast(2)
+            misspelledWord = misspelledWord.substring(0, newLength.coerceAtMost(misspelledWord.length))
+        }
+
+        return misspelledWord
+    }
+}
+
+const val TOKENIZER_BEGIN_USER_INPUT = "<XBU>"
+const val TOKENIZER_BEGIN_CORRECTION = "<XBC>"
+const val TOKENIZER_END_CORRECTION   = "<XEC>"
+private val TOKENIZER_LETTER_MAPPING = hashMapOf(
+    'a' to "<CHAR_A>",
+    'b' to "<CHAR_B>",
+    'c' to "<CHAR_C>",
+    'd' to "<CHAR_D>",
+    'e' to "<CHAR_E>",
+    'f' to "<CHAR_F>",
+    'g' to "<CHAR_G>",
+    'h' to "<CHAR_H>",
+    'i' to "<CHAR_I>",
+    'j' to "<CHAR_J>",
+    'k' to "<CHAR_K>",
+    'l' to "<CHAR_L>",
+    'm' to "<CHAR_M>",
+    'n' to "<CHAR_N>",
+    'o' to "<CHAR_O>",
+    'p' to "<CHAR_P>",
+    'q' to "<CHAR_Q>",
+    'r' to "<CHAR_R>",
+    's' to "<CHAR_S>",
+    't' to "<CHAR_T>",
+    'u' to "<CHAR_U>",
+    'v' to "<CHAR_V>",
+    'w' to "<CHAR_W>",
+    'x' to "<CHAR_X>",
+    'y' to "<CHAR_Y>",
+    'z' to "<CHAR_Z>",
+)
+
+private fun tokenizerFormatUserInput(misspelledWord: String): String {
+    return TOKENIZER_BEGIN_USER_INPUT + misspelledWord.mapNotNull { TOKENIZER_LETTER_MAPPING[it] }.joinToString(separator = "") + TOKENIZER_BEGIN_CORRECTION
+}
+
+object TrainingDataGenerator {
+    fun wordMisspelling(word: String): String {
+        val misspelled = WordMisspelling.misspellWord(word)
+
+        // Space after word is required for the tokenizer
+        return tokenizerFormatUserInput(misspelled) + word.trim() + " " + TOKENIZER_END_CORRECTION
+    }
+
+    private val permittedCharacters = "abcdefghijklmnopqrstuvwxyz'-".toHashSet()
+    fun suitableToMisspell(word: String): Boolean {
+        return permittedCharacters.containsAll(word.lowercase().toList())
+    }
+    fun randomlyMisspellWords(text: String, proportion: Float = 0.333f): String {
+        val words = text.split(" ").toMutableList()
+        val wordsToMisspell = mutableListOf<Int>()
+
+        for(i in 0 until (words.size * proportion).toInt()) {
+            val remainingIndices = words.indices.toSet().subtract(wordsToMisspell.toSet()).toList()
+            if(remainingIndices.isEmpty()) break;
+
+            val wordToMisspell = remainingIndices[Random.nextInt(remainingIndices.indices)]
+
+            if(suitableToMisspell(words[wordToMisspell])) {
+                wordsToMisspell.add(wordToMisspell)
+            }
+        }
+
+        wordsToMisspell.toSet().forEach { i ->
+            words[i] = wordMisspelling(words[i])
+        }
+
+        return words.joinToString(separator=" ").trim()
+            .replace("  ", " ")
+            .replace("  ", " ")
+            // Do not put spaces after these tokens, as it messes up tokenization
+            .replace("$TOKENIZER_BEGIN_CORRECTION ", TOKENIZER_BEGIN_CORRECTION)
+            .replace("$TOKENIZER_END_CORRECTION ", TOKENIZER_END_CORRECTION)
+    }
+}
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