org.apache.solr.client.solrj.io.eval.LoessEvaluator.java Source code

Introduction

Here is the source code for org.apache.solr.client.solrj.io.eval.LoessEvaluator.java

Source

/*
 * 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.client.solrj.io.eval;

import java.io.IOException;
import java.math.BigDecimal;
import java.util.List;
import java.util.ArrayList;

import org.apache.commons.math3.analysis.interpolation.LoessInterpolator;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionNamedParameter;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

public class LoessEvaluator extends RecursiveNumericEvaluator implements ManyValueWorker {
    protected static final long serialVersionUID = 1L;

    private double bandwidth = .25;
    private int robustIterations = 2;

    public LoessEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
        super(expression, factory);

        List<StreamExpressionNamedParameter> namedParams = factory.getNamedOperands(expression);

        for (StreamExpressionNamedParameter namedParam : namedParams) {
            if (namedParam.getName().equals("bandwidth")) {
                this.bandwidth = Double.parseDouble(namedParam.getParameter().toString().trim());
            } else if (namedParam.getName().equals("robustIterations")) {
                this.robustIterations = Integer.parseInt(namedParam.getParameter().toString().trim());
            } else {
                throw new IOException("Unexpected named parameter:" + namedParam.getName());
            }
        }

    }

    @Override
    public Object doWork(Object... objects) throws IOException {

        Object first = objects[0];

        double[] x = null;
        double[] y = null;

        if (objects.length == 1) {
            //Only the y values passed
            y = ((List) first).stream().mapToDouble(value -> ((BigDecimal) value).doubleValue()).toArray();
            x = new double[y.length];
            for (int i = 0; i < y.length; i++) {
                x[i] = i;
            }
        } else if (objects.length == 2) {
            Object second = objects[1];
            x = ((List) first).stream().mapToDouble(value -> ((BigDecimal) value).doubleValue()).toArray();
            y = ((List) second).stream().mapToDouble(value -> ((BigDecimal) value).doubleValue()).toArray();
        }

        LoessInterpolator interpolator = new LoessInterpolator(bandwidth, robustIterations);
        double[] smooth = interpolator.smooth(x, y);

        List list = new ArrayList();
        for (double yvalue : smooth) {
            list.add(yvalue);
        }

        return list;
    }
}