uk.ac.diamond.scisoft.analysis.dataset.function.Interpolation1D.java Source code

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Here is the source code for uk.ac.diamond.scisoft.analysis.dataset.function.Interpolation1D.java

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/*-
 * Copyright 2015 Diamond Light Source Ltd.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */

package uk.ac.diamond.scisoft.analysis.dataset.function;

import java.util.Arrays;
import java.util.Comparator;

import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.analysis.interpolation.LinearInterpolator;
import org.apache.commons.math3.analysis.interpolation.SplineInterpolator;
import org.apache.commons.math3.analysis.interpolation.UnivariateInterpolator;
import org.apache.commons.math3.exception.OutOfRangeException;
import org.eclipse.dawnsci.analysis.api.dataset.IDataset;
import org.eclipse.dawnsci.analysis.dataset.impl.Dataset;
import org.eclipse.dawnsci.analysis.dataset.impl.DatasetFactory;
import org.eclipse.dawnsci.analysis.dataset.impl.DatasetUtils;
import org.eclipse.dawnsci.analysis.dataset.impl.DoubleDataset;
import org.eclipse.dawnsci.analysis.dataset.impl.IntegerDataset;
import org.eclipse.dawnsci.analysis.dataset.roi.ROISliceUtils;

public class Interpolation1D {

    public static Dataset splineInterpolation(IDataset x, IDataset y, IDataset xnew) {

        return interpolate(x, y, xnew, new SplineInterpolator());

    }

    public static Dataset linearInterpolation(IDataset x, IDataset y, IDataset xnew) {

        return interpolate(x, y, xnew, new LinearInterpolator());

    }

    public static Dataset interpolate(IDataset oldx, IDataset oldy, IDataset newx,
            UnivariateInterpolator interpolator) {

        //TODO more sanity checks on inputs

        DoubleDataset dx = (DoubleDataset) DatasetUtils.cast(oldx, Dataset.FLOAT64);
        DoubleDataset dy = (DoubleDataset) DatasetUtils.cast(oldy, Dataset.FLOAT64);

        boolean sorted = true;
        double maxtest = dx.getDouble(0);
        int count = dx.getSize();
        for (int i = 1; i < count; i++) {
            if (maxtest > dx.getDouble(i)) {
                sorted = false;
                break;
            }
            maxtest = dx.getDouble(i);
        }

        double[] sortedx = null;
        double[] sortedy = null;

        if (!sorted) {
            IntegerDataset sIdx = getIndiciesOfSorted(dx);
            sortedx = new double[dx.getData().length];
            sortedy = new double[dy.getData().length];

            for (int i = 0; i < sIdx.getSize(); i++) {
                sortedx[i] = dx.getDouble(sIdx.get(i));
                sortedy[i] = dy.getDouble(sIdx.get(i));
            }
        } else {
            sortedx = dx.getData();
            sortedy = dy.getData();
        }

        UnivariateFunction func = interpolator.interpolate(sortedx, sortedy);

        Dataset newy = DatasetFactory.zeros(newx.getShape(), Dataset.FLOAT64);
        newy.setName(oldy.getName() + "_interpolated");
        count = newy.getSize();
        double val = 0;
        for (int i = 0; i < count; i++) {

            try {
                val = func.value(newx.getDouble(i));
            } catch (OutOfRangeException e) {
                val = 0;
            }

            newy.set(val, i);
        }

        return newy;
    }

    private static IntegerDataset getIndiciesOfSorted(final IDataset d) {

        Integer[] dBox = new Integer[d.getSize()];

        for (int i = 0; i < dBox.length; i++)
            dBox[i] = i;

        Arrays.sort(dBox, new Comparator<Integer>() {

            @Override
            public int compare(Integer o1, Integer o2) {
                double dif = d.getDouble(o1) - d.getDouble(o2);
                return dif > 0 ? (int) Math.ceil(dif) : (int) Math.floor(dif);
            }
        });

        int[] dint = new int[d.getSize()];
        for (int i = 0; i < dBox.length; i++)
            dint[i] = dBox[i];

        return new IntegerDataset(dint, new int[] { dint.length });
    }

    private static int[] getCommonRangeIndicies(IDataset x1, IDataset x2) {
        //TODO checks for no overlap etc
        double max1 = x1.max().doubleValue();
        double min1 = x1.min().doubleValue();

        double max2 = x2.max().doubleValue();
        double min2 = x2.min().doubleValue();

        double max = max1 < max2 ? max1 : max2;
        double min = min1 > min2 ? min1 : min2;
        //TODO max needs to be 1 lower, min needs to be 1 higher
        int maxpos = ROISliceUtils.findPositionOfClosestValueInAxis(x1, max);
        int minpos = ROISliceUtils.findPositionOfClosestValueInAxis(x1, min);

        return new int[] { minpos + 1, maxpos - 1 };
    }

}