EyeMoveArtifactAlgorithm.java

package org.signalml.plugin.newartifact.logic.algorithm;

import java.util.Arrays;

import org.signalml.plugin.domain.montage.PluginChannel;
import org.signalml.plugin.newartifact.data.NewArtifactConstants;
import org.signalml.plugin.newartifact.exception.NewArtifactPluginException;
import org.signalml.plugin.newartifact.logic.stat.Stat;

public class EyeMoveArtifactAlgorithm extends NewArtifactAlgorithmBase {

	private static double DEFAULT_EOG_CORRELATION = 7.0D;
	private static double DEFAULT_F78_CORRELATION = 8.0D;
	private static double DEFAULT_T34_CORRELATION = 9.0D;

	private Stat correlationAlgorithm;

	public EyeMoveArtifactAlgorithm(NewArtifactConstants constants) {
		super(constants);

		this.resultBuffer = new double[4][this.constants.channelCount];

		this.correlationAlgorithm = new Stat();
	}

	@Override
	public double[][] computeHead(NewArtifactAlgorithmData data) {
		return this.zeros(4, data.constants.channelCount);
	}

	@Override
	public double[][] computeTail(NewArtifactAlgorithmData data) {
		return this.zeros(4, data.constants.channelCount);
	}

	@Override
	public double[][] compute(NewArtifactAlgorithmData data) {
		int blockLength = data.constants.getBlockLength();
		int tailLength = data.constants.getPaddingLength();

		PreprocessHelper.Preprocess(data.signal, data.constants);

		double signal[][] = new double[data.signal.length][];
		for (int i = 0; i < signal.length; ++i) {
			signal[i] = Arrays.copyOfRange(data.signal[i], tailLength,
										   blockLength + tailLength);
		}

		double resultBuffer[] = this.resultBuffer[3];
		Arrays.fill(resultBuffer, 0.0D);

		resultBuffer[0] = this.computeCorrelation(signal, data,
						  PluginChannel.EOGL, PluginChannel.EOGP, 0,
						  EyeMoveArtifactAlgorithm.DEFAULT_EOG_CORRELATION);
		resultBuffer[1] = this.computeCorrelation(signal, data,
						  PluginChannel.F7, PluginChannel.F8, 1,
						  EyeMoveArtifactAlgorithm.DEFAULT_F78_CORRELATION);
		resultBuffer[2] = this.computeCorrelation(signal, data,
						  PluginChannel.T3, PluginChannel.T4, 2,
						  EyeMoveArtifactAlgorithm.DEFAULT_T34_CORRELATION);

		return this.resultBuffer;
	}

	private double computeCorrelation(double signal[][],
									  NewArtifactAlgorithmData data, PluginChannel channel1,
									  PluginChannel channel2, int resultColumn, double defaultValue) {
		int channelNumber1, channelNumber2;
		try {
			channelNumber1 = this.getChannelNumber(data, channel1);
			channelNumber2 = this.getChannelNumber(data, channel2);
		} catch (NewArtifactPluginException e) {
			return defaultValue;
		}

		this.computeSingleCorrelation(signal, channelNumber1, channelNumber2,
									  resultColumn);
		return this.correlationAlgorithm.computeCorrelation(
				   signal[channelNumber1], signal[channelNumber2]);
	}

	private void computeSingleCorrelation(double signal[][], int channel1,
										  int channel2, int resultColumn) {
		double channel1Data[] = signal[channel1];
		double channel2Data[] = signal[channel2];
		double resultBuffer[] = this.resultBuffer[resultColumn];

		for (int i = 0; i < signal.length; ++i) {
			if (i != channel1 && i != channel2) {
				double c1 = this.correlationAlgorithm.computeCorrelation(
								channel1Data, signal[i]);
				double c2 = this.correlationAlgorithm.computeCorrelation(
								channel2Data, signal[i]);
				resultBuffer[i] = Math.max(Math.abs(c1), Math.abs(c2));
			} else {
				resultBuffer[i] = 0;
			}
		}
	}
}