Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 org.apache.lucene.document; import java.util.Arrays; import java.util.Collection; import org.apache.lucene.index.PointValues; import org.apache.lucene.search.PointInSetQuery; import org.apache.lucene.search.PointRangeQuery; import org.apache.lucene.search.Query; import org.apache.lucene.util.BytesRef; import org.apache.lucene.util.NumericUtils; /** * An indexed {@code float} field for fast range filters. If you also * need to store the value, you should add a separate {@link StoredField} instance. * <p> * Finding all documents within an N-dimensional at search time is * efficient. Multiple values for the same field in one document * is allowed. * <p> * This field defines static factory methods for creating common queries: * <ul> * <li>{@link #newExactQuery(String, float)} for matching an exact 1D point. * <li>{@link #newSetQuery(String, float...)} for matching a set of 1D values. * <li>{@link #newRangeQuery(String, float, float)} for matching a 1D range. * <li>{@link #newRangeQuery(String, float[], float[])} for matching points/ranges in n-dimensional space. * </ul> * @see PointValues */ public final class FloatPoint extends Field { /** * Return the least float that compares greater than {@code f} consistently * with {@link Float#compare}. The only difference with * {@link Math#nextUp(float)} is that this method returns {@code +0f} when * the argument is {@code -0f}. */ public static float nextUp(float f) { if (Float.floatToIntBits(f) == 0x8000_0000) { // -0f return +0f; } return Math.nextUp(f); } /** * Return the greatest float that compares less than {@code f} consistently * with {@link Float#compare}. The only difference with * {@link Math#nextDown(float)} is that this method returns {@code -0f} when * the argument is {@code +0f}. */ public static float nextDown(float f) { if (Float.floatToIntBits(f) == 0) { // +0f return -0f; } return Math.nextDown(f); } private static FieldType getType(int numDims) { FieldType type = new FieldType(); type.setDimensions(numDims, Float.BYTES); type.freeze(); return type; } @Override public void setFloatValue(float value) { setFloatValues(value); } /** Change the values of this field */ public void setFloatValues(float... point) { if (type.pointDataDimensionCount() != point.length) { throw new IllegalArgumentException( "this field (name=" + name + ") uses " + type.pointDataDimensionCount() + " dimensions; cannot change to (incoming) " + point.length + " dimensions"); } fieldsData = pack(point); } @Override public void setBytesValue(BytesRef bytes) { throw new IllegalArgumentException("cannot change value type from float to BytesRef"); } @Override public Number numericValue() { if (type.pointDataDimensionCount() != 1) { throw new IllegalStateException("this field (name=" + name + ") uses " + type.pointDataDimensionCount() + " dimensions; cannot convert to a single numeric value"); } BytesRef bytes = (BytesRef) fieldsData; assert bytes.length == Float.BYTES; return decodeDimension(bytes.bytes, bytes.offset); } /** * Pack a float point into a BytesRef * * @param point float[] value * @throws IllegalArgumentException is the value is null or of zero length */ public static BytesRef pack(float... point) { if (point == null) { throw new IllegalArgumentException("point must not be null"); } if (point.length == 0) { throw new IllegalArgumentException("point must not be 0 dimensions"); } byte[] packed = new byte[point.length * Float.BYTES]; for (int dim = 0; dim < point.length; dim++) { encodeDimension(point[dim], packed, dim * Float.BYTES); } return new BytesRef(packed); } /** Creates a new FloatPoint, indexing the * provided N-dimensional float point. * * @param name field name * @param point float[] value * @throws IllegalArgumentException if the field name or value is null. */ public FloatPoint(String name, float... point) { super(name, pack(point), getType(point.length)); } @Override public String toString() { StringBuilder result = new StringBuilder(); result.append(getClass().getSimpleName()); result.append(" <"); result.append(name); result.append(':'); BytesRef bytes = (BytesRef) fieldsData; for (int dim = 0; dim < type.pointDataDimensionCount(); dim++) { if (dim > 0) { result.append(','); } result.append(decodeDimension(bytes.bytes, bytes.offset + dim * Float.BYTES)); } result.append('>'); return result.toString(); } // public helper methods (e.g. for queries) /** Encode single float dimension */ public static void encodeDimension(float value, byte dest[], int offset) { NumericUtils.intToSortableBytes(NumericUtils.floatToSortableInt(value), dest, offset); } /** Decode single float dimension */ public static float decodeDimension(byte value[], int offset) { return NumericUtils.sortableIntToFloat(NumericUtils.sortableBytesToInt(value, offset)); } // static methods for generating queries /** * Create a query for matching an exact float value. * <p> * This is for simple one-dimension points, for multidimensional points use * {@link #newRangeQuery(String, float[], float[])} instead. * * @param field field name. must not be {@code null}. * @param value float value * @throws IllegalArgumentException if {@code field} is null. * @return a query matching documents with this exact value */ public static Query newExactQuery(String field, float value) { return newRangeQuery(field, value, value); } /** * Create a range query for float values. * <p> * This is for simple one-dimension ranges, for multidimensional ranges use * {@link #newRangeQuery(String, float[], float[])} instead. * <p> * You can have half-open ranges (which are in fact </≤ or >/≥ queries) * by setting {@code lowerValue = Float.NEGATIVE_INFINITY} or {@code upperValue = Float.POSITIVE_INFINITY}. * <p> Ranges are inclusive. For exclusive ranges, pass {@link #nextUp(float) nextUp(lowerValue)} * or {@link #nextUp(float) nextDown(upperValue)}. * <p> * Range comparisons are consistent with {@link Float#compareTo(Float)}. * * @param field field name. must not be {@code null}. * @param lowerValue lower portion of the range (inclusive). * @param upperValue upper portion of the range (inclusive). * @throws IllegalArgumentException if {@code field} is null. * @return a query matching documents within this range. */ public static Query newRangeQuery(String field, float lowerValue, float upperValue) { return newRangeQuery(field, new float[] { lowerValue }, new float[] { upperValue }); } /** * Create a range query for n-dimensional float values. * <p> * You can have half-open ranges (which are in fact </≤ or >/≥ queries) * by setting {@code lowerValue[i] = Float.NEGATIVE_INFINITY} or {@code upperValue[i] = Float.POSITIVE_INFINITY}. * <p> Ranges are inclusive. For exclusive ranges, pass {@code Math#nextUp(lowerValue[i])} * or {@code Math.nextDown(upperValue[i])}. * <p> * Range comparisons are consistent with {@link Float#compareTo(Float)}. * * @param field field name. must not be {@code null}. * @param lowerValue lower portion of the range (inclusive). must not be {@code null}. * @param upperValue upper portion of the range (inclusive). must not be {@code null}. * @throws IllegalArgumentException if {@code field} is null, if {@code lowerValue} is null, if {@code upperValue} is null, * or if {@code lowerValue.length != upperValue.length} * @return a query matching documents within this range. */ public static Query newRangeQuery(String field, float[] lowerValue, float[] upperValue) { PointRangeQuery.checkArgs(field, lowerValue, upperValue); return new PointRangeQuery(field, pack(lowerValue).bytes, pack(upperValue).bytes, lowerValue.length) { @Override protected String toString(int dimension, byte[] value) { return Float.toString(decodeDimension(value, 0)); } }; } /** * Create a query matching any of the specified 1D values. This is the points equivalent of {@code TermsQuery}. * * @param field field name. must not be {@code null}. * @param values all values to match */ public static Query newSetQuery(String field, float... values) { // Don't unexpectedly change the user's incoming values array: float[] sortedValues = values.clone(); Arrays.sort(sortedValues); final BytesRef encoded = new BytesRef(new byte[Float.BYTES]); return new PointInSetQuery(field, 1, Float.BYTES, new PointInSetQuery.Stream() { int upto; @Override public BytesRef next() { if (upto == sortedValues.length) { return null; } else { encodeDimension(sortedValues[upto], encoded.bytes, 0); upto++; return encoded; } } }) { @Override protected String toString(byte[] value) { assert value.length == Float.BYTES; return Float.toString(decodeDimension(value, 0)); } }; } /** * Create a query matching any of the specified 1D values. This is the points equivalent of {@code TermsQuery}. * * @param field field name. must not be {@code null}. * @param values all values to match */ public static Query newSetQuery(String field, Collection<Float> values) { Float[] boxed = values.toArray(new Float[0]); float[] unboxed = new float[boxed.length]; for (int i = 0; i < boxed.length; i++) { unboxed[i] = boxed[i]; } return newSetQuery(field, unboxed); } }