/*
* Copyright (c) 2014, Cloudera and Intel, Inc. All Rights Reserved.
*
* Cloudera, Inc. 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
*
* This software 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.cloudera.oryx.ml.serving.als;
import java.util.ArrayList;
import java.util.List;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.PathSegment;
import com.google.common.base.Preconditions;
import com.cloudera.oryx.common.math.VectorMath;
import com.cloudera.oryx.ml.serving.CSVMessageBodyWriter;
import com.cloudera.oryx.ml.serving.OryxServingException;
import com.cloudera.oryx.ml.serving.als.model.ALSServingModel;
/**
* <p>Responds to a GET request to {@code /similarityToItem/[toItemID]/[itemID1](/[itemID2]/...)}.
*
* <p>This computes cosine similarity between an item and one or more other items.</p>
*
* <p>The output are similarities, in the same order as the item IDs, with format
* as in {@link Estimate}</p>
*/
@Path("/similarityToItem")
public final class SimilarityToItem extends AbstractALSResource {
@GET
@Path("{toItemID}/{itemID : .+}")
@Produces({CSVMessageBodyWriter.TEXT_CSV, MediaType.APPLICATION_JSON})
public List<Double> get(
@PathParam("toItemID") String toItemID,
@PathParam("itemID") List<PathSegment> pathSegmentsList) throws OryxServingException {
ALSServingModel alsServingModel = getALSServingModel();
float[] toItemFeatures = alsServingModel.getItemVector(toItemID);
checkExists(toItemFeatures != null, toItemID);
double toItemFeaturesNorm = VectorMath.norm(toItemFeatures);
List<Double> results = new ArrayList<>(pathSegmentsList.size());
for (PathSegment item : pathSegmentsList) {
float[] itemFeatures = alsServingModel.getItemVector(item.getPath());
if (itemFeatures == null) {
results.add(0.0);
} else {
double value = VectorMath.dot(itemFeatures, toItemFeatures) /
(toItemFeaturesNorm * VectorMath.norm(itemFeatures));
Preconditions.checkState(!(Double.isInfinite(value) || Double.isNaN(value)), "Bad similarity");
results.add(value);
}
}
return results;
}
}