Add utils for forgetting curve (607a9244) · Commits · e / os / android_packages_inputmethods_LatinIME

java/src/com/android/inputmethod/latin/UserHistoryForgettingCurveUtils.java

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		/*
		* Copyright (C) 2012 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package com.android.inputmethod.latin;

		public class UserHistoryForgettingCurveUtils {
		private static final int FC_FREQ_MAX = 127;
		/* package */ static final int COUNT_MAX = 3;
		private static final int FC_LEVEL_MAX = 3;
		/* package */ static final int ELAPSED_TIME_MAX = 15;
		private static final int ELAPSED_TIME_INTERVAL_HOURS = 6;
		private static final int HALF_LIFE_HOURS = 48;

		/* package */ static int fcToElapsedTime(byte fc) {
		return fc & 0x0F;
		}

		/* package */ static int fcToCount(byte fc) {
		return (fc >> 4) & 0x03;
		}

		/* package */ static int fcToLevel(byte fc) {
		return (fc >> 6) & 0x03;
		}

		private static int calcFreq(int elapsedTime, int count, int level) {
		if (level <= 0) {
		// Reserved words, just return 0
		return 0;
		}
		if (count == COUNT_MAX) {
		// Temporary promote because it's frequently typed recently
		++level;
		}
		final int et = Math.min(FC_FREQ_MAX, Math.max(0, elapsedTime));
		final int l = Math.min(FC_LEVEL_MAX, Math.max(0, level));
		return MathUtils.SCORE_TABLE[l - 1][et];
		}

		/* pakcage */ static byte calcFc(int elapsedTime, int count, int level) {
		final int et = Math.min(FC_FREQ_MAX, Math.max(0, elapsedTime));
		final int c = Math.min(COUNT_MAX, Math.max(0, count));
		final int l = Math.min(FC_LEVEL_MAX, Math.max(0, level));
		return (byte)(et \| (c << 4) \| (l << 6));
		}

		public static int fcToFreq(byte fc) {
		final int elapsedTime = fcToElapsedTime(fc);
		final int count = fcToCount(fc);
		final int level = fcToLevel(fc);
		return calcFreq(elapsedTime, count, level);
		}

		public static byte pushElapsedTime(byte fc) {
		int elapsedTime = fcToElapsedTime(fc);
		int count = fcToCount(fc);
		int level = fcToLevel(fc);
		if (elapsedTime >= ELAPSED_TIME_MAX) {
		// Downgrade level
		elapsedTime = 0;
		count = COUNT_MAX;
		--level;
		} else {
		++elapsedTime;
		}
		return calcFc(elapsedTime, count, level);
		}

		public static byte pushCount(byte fc, boolean isValid) {
		final int elapsedTime = fcToElapsedTime(fc);
		int count = fcToCount(fc);
		int level = fcToLevel(fc);
		if ((elapsedTime == 0 && count >= COUNT_MAX) \|\| (isValid && level == 0)) {
		// Upgrade level
		++level;
		count = 0;
		} else {
		++count;
		}
		return calcFc(0, count, level);
		}

		private static class MathUtils {
		public static final int[][] SCORE_TABLE = new int[FC_LEVEL_MAX][ELAPSED_TIME_MAX + 1];
		static {
		for (int i = 0; i < FC_LEVEL_MAX; ++i) {
		final double initialFreq;
		if (i >= 2) {
		initialFreq = (double)FC_FREQ_MAX;
		} else if (i == 1) {
		initialFreq = (double)FC_FREQ_MAX / 2;
		} else if (i == 0) {
		initialFreq = (double)FC_FREQ_MAX / 4;
		} else {
		continue;
		}
		for (int j = 0; j < ELAPSED_TIME_MAX; ++j) {
		final double elapsedHour = j * ELAPSED_TIME_INTERVAL_HOURS;
		final double freq =
		initialFreq * Math.pow(initialFreq, elapsedHour / HALF_LIFE_HOURS);
		final int intFreq = Math.min(FC_FREQ_MAX, Math.max(0, (int)freq));
		SCORE_TABLE[i][j] = intFreq;
		}
		}
		}
		}
		}

tests/src/com/android/inputmethod/latin/ForgettingCurveTests.java

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		/*
		* Copyright (C) 2012 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package com.android.inputmethod.latin;

		import android.test.AndroidTestCase;

		public class ForgettingCurveTests extends AndroidTestCase {
		public void testFcToFreq() {
		for (int i = 0; i < Byte.MAX_VALUE; ++i) {
		final byte fc = (byte)i;
		final int e = UserHistoryForgettingCurveUtils.fcToElapsedTime(fc);
		final int c = UserHistoryForgettingCurveUtils.fcToCount(fc);
		final int l = UserHistoryForgettingCurveUtils.fcToLevel(fc);
		final byte fc2 = UserHistoryForgettingCurveUtils.calcFc(e, c, l);
		assertEquals(fc, fc2);
		}
		byte fc = 0;
		int l;
		for (int i = 0; i < 4; ++i) {
		for (int j = 0; j < (UserHistoryForgettingCurveUtils.COUNT_MAX + 1); ++j) {
		fc = UserHistoryForgettingCurveUtils.pushCount(fc, true);
		}
		l = UserHistoryForgettingCurveUtils.fcToLevel(fc);
		assertEquals(l, Math.max(1, Math.min(i + 1, 3)));
		}
		fc = 0;
		for (int i = 0; i < 4; ++i) {
		for (int j = 0; j < (UserHistoryForgettingCurveUtils.COUNT_MAX + 1); ++j) {
		fc = UserHistoryForgettingCurveUtils.pushCount(fc, false);
		}
		l = UserHistoryForgettingCurveUtils.fcToLevel(fc);
		assertEquals(l, Math.min(i + 1, 3));
		}
		for (int i = 0; i < 4; ++i) {
		for (int j = 0; j < (UserHistoryForgettingCurveUtils.ELAPSED_TIME_MAX + 1); ++j) {
		fc = UserHistoryForgettingCurveUtils.pushElapsedTime(fc);
		}
		l = UserHistoryForgettingCurveUtils.fcToLevel(fc);
		assertEquals(l, Math.max(0, 2 - i));
		}
		}
		}