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vil02BamaCharanChhandogi
vil02
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BamaCharanChhandogi
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feat: add temperature unit conversions (#5315)
Co-authored-by: Bama Charan Chhandogi <[email protected]>
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‎src/main/java/com/thealgorithms/conversions/AffineConverter.java

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package com.thealgorithms.conversions;
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public final class AffineConverter {
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private final double slope;
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private final double intercept;
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public AffineConverter(final double inSlope, final double inIntercept) {
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slope = inSlope;
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intercept = inIntercept;
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}
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public double convert(final double inValue) {
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return slope * inValue + intercept;
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}
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public AffineConverter invert() {
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assert slope != 0.0;
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return new AffineConverter(1.0 / slope, -intercept / slope);
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}
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public AffineConverter compose(final AffineConverter other) {
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return new AffineConverter(slope * other.slope, slope * other.intercept + intercept);
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}
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}

‎src/main/java/com/thealgorithms/conversions/UnitConversions.java

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package com.thealgorithms.conversions;
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import static java.util.Map.entry;
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import java.util.Map;
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import org.apache.commons.lang3.tuple.Pair;
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public final class UnitConversions {
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private UnitConversions() {
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}
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public static final UnitsConverter TEMPERATURE = new UnitsConverter(Map.ofEntries(entry(Pair.of("Kelvin", "Celsius"), new AffineConverter(1.0, -273.15)), entry(Pair.of("Celsius", "Fahrenheit"), new AffineConverter(9.0 / 5.0, 32.0)),
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entry(Pair.of("Réaumur", "Celsius"), new AffineConverter(5.0 / 4.0, 0.0)), entry(Pair.of("Delisle", "Celsius"), new AffineConverter(-2.0 / 3.0, 100.0)), entry(Pair.of("Rankine", "Kelvin"), new AffineConverter(5.0 / 9.0, 0.0))));
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}

‎src/main/java/com/thealgorithms/conversions/UnitsConverter.java

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package com.thealgorithms.conversions;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Set;
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import org.apache.commons.lang3.tuple.Pair;
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public final class UnitsConverter {
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private final Map<Pair<String, String>, AffineConverter> conversions;
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private final Set<String> units;
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private static void putIfNeeded(Map<Pair<String, String>, AffineConverter> conversions, final String inputUnit, final String outputUnit, final AffineConverter converter) {
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if (!inputUnit.equals(outputUnit)) {
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final var key = Pair.of(inputUnit, outputUnit);
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conversions.putIfAbsent(key, converter);
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}
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}
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private static Map<Pair<String, String>, AffineConverter> addInversions(final Map<Pair<String, String>, AffineConverter> knownConversions) {
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Map<Pair<String, String>, AffineConverter> res = new HashMap<Pair<String, String>, AffineConverter>();
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for (final var curConversion : knownConversions.entrySet()) {
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final var inputUnit = curConversion.getKey().getKey();
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final var outputUnit = curConversion.getKey().getValue();
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putIfNeeded(res, inputUnit, outputUnit, curConversion.getValue());
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putIfNeeded(res, outputUnit, inputUnit, curConversion.getValue().invert());
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}
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return res;
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}
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private static Map<Pair<String, String>, AffineConverter> addCompositions(final Map<Pair<String, String>, AffineConverter> knownConversions) {
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Map<Pair<String, String>, AffineConverter> res = new HashMap<Pair<String, String>, AffineConverter>();
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for (final var first : knownConversions.entrySet()) {
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final var firstKey = first.getKey();
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putIfNeeded(res, firstKey.getKey(), firstKey.getValue(), first.getValue());
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for (final var second : knownConversions.entrySet()) {
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final var secondKey = second.getKey();
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if (firstKey.getValue().equals(secondKey.getKey())) {
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final var newConversion = second.getValue().compose(first.getValue());
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putIfNeeded(res, firstKey.getKey(), secondKey.getValue(), newConversion);
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}
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}
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}
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return res;
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}
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private static Map<Pair<String, String>, AffineConverter> addAll(final Map<Pair<String, String>, AffineConverter> knownConversions) {
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final var res = addInversions(knownConversions);
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return addCompositions(res);
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}
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private static Map<Pair<String, String>, AffineConverter> computeAllConversions(final Map<Pair<String, String>, AffineConverter> basicConversions) {
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var tmp = basicConversions;
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var res = addAll(tmp);
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while (res.size() != tmp.size()) {
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tmp = res;
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res = addAll(tmp);
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}
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return res;
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}
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private static Set<String> extractUnits(final Map<Pair<String, String>, AffineConverter> conversions) {
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Set<String> res = new HashSet<>();
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for (final var conversion : conversions.entrySet()) {
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res.add(conversion.getKey().getKey());
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}
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return res;
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}
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public UnitsConverter(final Map<Pair<String, String>, AffineConverter> basicConversions) {
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conversions = computeAllConversions(basicConversions);
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units = extractUnits(conversions);
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}
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public double convert(final String inputUnit, final String outputUnit, final double value) {
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if (inputUnit.equals(outputUnit)) {
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throw new IllegalArgumentException("inputUnit must be different from outputUnit.");
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}
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final var conversionKey = Pair.of(inputUnit, outputUnit);
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return conversions.get(conversionKey).convert(value);
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}
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public Set<String> availableUnits() {
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return units;
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}
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}

‎src/test/java/com/thealgorithms/conversions/UnitConversionsTest.java

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package com.thealgorithms.conversions;
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import static java.util.Map.entry;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.util.Map;
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import java.util.Set;
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import java.util.stream.Stream;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.Arguments;
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import org.junit.jupiter.params.provider.MethodSource;
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public class UnitConversionsTest {
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private static void addData(Stream.Builder<Arguments> builder, Map<String, Double> values) {
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for (final var first : values.entrySet()) {
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for (final var second : values.entrySet()) {
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if (!first.getKey().equals(second.getKey())) {
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builder.add(Arguments.of(first.getKey(), second.getKey(), first.getValue(), second.getValue()));
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}
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}
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}
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}
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private static Stream<Arguments> temperatureData() {
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final Map<String, Double> boilingPointOfWater = Map.ofEntries(entry("Celsius", 99.9839), entry("Fahrenheit", 211.97102), entry("Kelvin", 373.1339), entry("Réaumur", 79.98712), entry("Delisle", 0.02415), entry("Rankine", 671.64102));
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final Map<String, Double> freezingPointOfWater = Map.ofEntries(entry("Celsius", 0.0), entry("Fahrenheit", 32.0), entry("Kelvin", 273.15), entry("Réaumur", 0.0), entry("Delisle", 150.0), entry("Rankine", 491.67));
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Stream.Builder<Arguments> builder = Stream.builder();
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addData(builder, boilingPointOfWater);
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addData(builder, freezingPointOfWater);
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return builder.build();
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}
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@ParameterizedTest
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@MethodSource("temperatureData")
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void testTemperature(String inputUnit, String outputUnit, double value, double expected) {
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final double result = UnitConversions.TEMPERATURE.convert(inputUnit, outputUnit, value);
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assertEquals(expected, result, 0.00001);
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}
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@Test
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void testTemperatureUnits() {
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final Set<String> expectedUnits = Set.of("Celsius", "Fahrenheit", "Kelvin", "Réaumur", "Rankine", "Delisle");
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assertEquals(expectedUnits, UnitConversions.TEMPERATURE.availableUnits());
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}
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}

‎src/test/java/com/thealgorithms/conversions/UnitsConverterTest.java

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package com.thealgorithms.conversions;
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import static java.util.Map.entry;
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import static org.junit.jupiter.api.Assertions.assertThrows;
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import java.util.Map;
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import org.apache.commons.lang3.tuple.Pair;
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import org.junit.jupiter.api.Test;
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public class UnitsConverterTest {
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@Test
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void testConvertThrowsForSameUnits() {
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final UnitsConverter someConverter = new UnitsConverter(Map.ofEntries(entry(Pair.of("A", "B"), new AffineConverter(10.0, -20.0))));
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assertThrows(IllegalArgumentException.class, () -> someConverter.convert("A", "A", 20.0));
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assertThrows(IllegalArgumentException.class, () -> someConverter.convert("B", "B", 20.0));
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}
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}

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