/*
* 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.queries.function.valuesource;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.ReaderUtil;
import org.apache.lucene.queries.function.FunctionValues;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.docvalues.FloatDocValues;
import org.apache.lucene.search.IndexSearcher;
import java.io.IOException;
import java.util.List;
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 + ")";
}
private static class ScaleInfo {
float minVal;
float maxVal;
}
private ScaleInfo createScaleInfo(Map context, AtomicReaderContext readerContext) throws IOException {
final List<AtomicReaderContext> leaves = ReaderUtil.getTopLevelContext(readerContext).leaves();
float minVal = Float.POSITIVE_INFINITY;
float maxVal = Float.NEGATIVE_INFINITY;
for (AtomicReaderContext leaf : leaves) {
int maxDoc = leaf.reader().maxDoc();
FunctionValues vals = source.getValues(context, leaf);
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;
}
if (val > maxVal) {
maxVal = val;
}
}
}
if (minVal == Float.POSITIVE_INFINITY) {
// must have been an empty index
minVal = maxVal = 0;
}
ScaleInfo scaleInfo = new ScaleInfo();
scaleInfo.minVal = minVal;
scaleInfo.maxVal = maxVal;
context.put(ScaleFloatFunction.this, scaleInfo);
return scaleInfo;
}
@Override
public FunctionValues getValues(Map context, AtomicReaderContext readerContext) throws IOException {
ScaleInfo scaleInfo = (ScaleInfo)context.get(ScaleFloatFunction.this);
if (scaleInfo == null) {
scaleInfo = createScaleInfo(context, readerContext);
}
final float scale = (scaleInfo.maxVal-scaleInfo.minVal==0) ? 0 : (max-min)/(scaleInfo.maxVal-scaleInfo.minVal);
final float minSource = scaleInfo.minVal;
final float maxSource = scaleInfo.maxVal;
final FunctionValues vals = source.getValues(context, readerContext);
return new FloatDocValues(this) {
@Override
public float floatVal(int doc) {
return (vals.floatVal(doc) - minSource) * scale + min;
}
@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, IndexSearcher 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);
}
}