org.apache.solr.search.function.ScaleFloatFunction.java Source code

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Here is the source code for org.apache.solr.search.function.ScaleFloatFunction.java

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/**
 * 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.solr.search.function;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Searcher;

import java.io.IOException;
import java.util.Map;

/**
 * Scales values to be between min and max.
 * <p>This implementation currently traverses all of the source values to obtain
 * their min and max.
 * <p>This implementation currently cannot distinguish when documents have been
 * deleted or documents that have no value, and 0.0 values will be used for
 * these cases.  This means that if values are normally all greater than 0.0, one can
 * still end up with 0.0 as the min value to map from.  In these cases, an
 * appropriate map() function could be used as a workaround to change 0.0
 * to a value in the real range.
 */
public class ScaleFloatFunction extends ValueSource {
    protected final ValueSource source;
    protected final float min;
    protected final float max;

    public ScaleFloatFunction(ValueSource source, float min, float max) {
        this.source = source;
        this.min = min;
        this.max = max;
    }

    @Override
    public String description() {
        return "scale(" + source.description() + "," + min + "," + max + ")";
    }

    @Override
    public DocValues getValues(Map context, IndexReader reader) throws IOException {
        final DocValues vals = source.getValues(context, reader);
        int maxDoc = reader.maxDoc();

        // this doesn't take into account deleted docs!
        float minVal = 0.0f;
        float maxVal = 0.0f;

        if (maxDoc > 0) {
            minVal = maxVal = vals.floatVal(0);
        }

        // Traverse the complete set of values to get the min and the max.
        // Future alternatives include being able to ask a DocValues for min/max
        // Another memory-intensive option is to cache the values in
        // a float[] on this first pass.

        for (int i = 0; i < maxDoc; i++) {
            float val = vals.floatVal(i);
            if ((Float.floatToRawIntBits(val) & (0xff << 23)) == 0xff << 23) {
                // if the exponent in the float is all ones, then this is +Inf, -Inf or NaN
                // which don't make sense to factor into the scale function
                continue;
            }
            if (val < minVal) {
                minVal = val;
            } else if (val > maxVal) {
                maxVal = val;
            }
        }

        final float scale = (maxVal - minVal == 0) ? 0 : (max - min) / (maxVal - minVal);
        final float minSource = minVal;
        final float maxSource = maxVal;

        return new DocValues() {
            @Override
            public float floatVal(int doc) {
                return (vals.floatVal(doc) - minSource) * scale + min;
            }

            @Override
            public int intVal(int doc) {
                return (int) floatVal(doc);
            }

            @Override
            public long longVal(int doc) {
                return (long) floatVal(doc);
            }

            @Override
            public double doubleVal(int doc) {
                return (double) floatVal(doc);
            }

            @Override
            public String strVal(int doc) {
                return Float.toString(floatVal(doc));
            }

            @Override
            public String toString(int doc) {
                return "scale(" + vals.toString(doc) + ",toMin=" + min + ",toMax=" + max + ",fromMin=" + minSource
                        + ",fromMax=" + maxSource + ")";
            }
        };
    }

    @Override
    public void createWeight(Map context, Searcher searcher) throws IOException {
        source.createWeight(context, searcher);
    }

    @Override
    public int hashCode() {
        int h = Float.floatToIntBits(min);
        h = h * 29;
        h += Float.floatToIntBits(max);
        h = h * 29;
        h += source.hashCode();
        return h;
    }

    @Override
    public boolean equals(Object o) {
        if (ScaleFloatFunction.class != o.getClass())
            return false;
        ScaleFloatFunction other = (ScaleFloatFunction) o;
        return this.min == other.min && this.max == other.max && this.source.equals(other.source);
    }
}