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

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Here is the source code for org.apache.solr.client.solrj.io.eval.SplineEvaluator.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.client.solrj.io.eval;

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

import org.apache.commons.math3.analysis.interpolation.SplineInterpolator;
import org.apache.commons.math3.analysis.polynomials.PolynomialSplineFunction;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

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

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

    @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 -> ((Number) 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 -> ((Number) value).doubleValue()).toArray();
            y = ((List) second).stream().mapToDouble(value -> ((Number) value).doubleValue()).toArray();
        }

        SplineInterpolator interpolator = new SplineInterpolator();
        PolynomialSplineFunction spline = interpolator.interpolate(x, y);

        List<Number> list = new ArrayList();
        for (double xvalue : x) {
            list.add(spline.value(xvalue));
        }

        VectorFunction vec = new VectorFunction(spline, list);
        vec.addToContext("x", x);
        vec.addToContext("y", y);

        return vec;
    }

}