com.cloudera.oryx.kmeans.serving.web.DistanceToNearestServlet.java Source code

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Here is the source code for com.cloudera.oryx.kmeans.serving.web.DistanceToNearestServlet.java

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/*
 * Copyright (c) 2013, Cloudera, 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.kmeans.serving.web;

import com.cloudera.oryx.kmeans.common.Centers;
import com.cloudera.oryx.kmeans.common.Distance;
import com.google.common.base.Preconditions;
import org.apache.commons.math3.linear.RealVector;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

import com.cloudera.oryx.common.io.DelimitedDataUtils;
import com.cloudera.oryx.kmeans.serving.generation.Generation;

/**
 * <p>Responsds to a GET request to {@code /distanceToNearest/[datum]}. The input is one data point to cluster,
 * delimited, like "1,-4,3.0". The response body contains the distance to the nearest cluster, on one line.</p>
 *
 * @author Sean Owen
 */
public final class DistanceToNearestServlet extends AbstractKMeansServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        CharSequence pathInfo = request.getPathInfo();
        if (pathInfo == null) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No path");
            return;
        }
        String line = pathInfo.subSequence(1, pathInfo.length()).toString();

        Generation generation = getGenerationManager().getCurrentGeneration();
        if (generation == null) {
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                    "API method unavailable until model has been built and loaded");
            return;
        }

        String[] tokens = DelimitedDataUtils.decode(line);
        RealVector vector = generation.toVector(tokens);
        if (vector == null) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Wrong column count");
            return;
        }
        double distance = findClosest(generation, vector).getSquaredDistance();
        response.getWriter().write(Double.toString(distance));
    }

    static Distance findClosest(Generation generation, RealVector parsedVector) {
        Centers centroids = generation.getCentroids();
        Preconditions.checkState(centroids.size() > 0);
        return centroids.getDistance(parsedVector);
    }
}