Examples with SkewNormalFunction gdsc.smlm.function.SkewNormalFunction used on opensource projects

Example 1 with SkewNormalFunction

use of gdsc.smlm.function.SkewNormalFunction in project GDSC-SMLM by aherbert.

the class PCPALMMolecules method addToPlot.

/**
	 * Add the skewed gaussian to the histogram plot
	 * 
	 * @param plot
	 * @param x
	 * @param parameters
	 *            Gaussian parameters
	 * @param alpha
	 * @param shape
	 */
private void addToPlot(Plot2 plot, float[] x, double[] parameters, int shape) {
    SkewNormalFunction sn = new SkewNormalFunction(parameters);
    float[] y = new float[x.length];
    for (int i = 0; i < x.length; i++) y[i] = (float) sn.evaluate(x[i]);
    plot.addPoints(x, y, shape);
}

Example 2 with SkewNormalFunction

use of gdsc.smlm.function.SkewNormalFunction in project GDSC-SMLM by aherbert.

the class PCPALMMolecules method calculateAveragePrecision.

/**
	 * Calculate the average precision by fitting a skewed Gaussian to the histogram of the precision distribution.
	 * <p>
	 * A simple mean and SD of the histogram is computed. If the mean of the Skewed Gaussian does not fit within 3 SDs
	 * of the simple mean then the simple mean is returned.
	 * 
	 * @param molecules
	 * @param title
	 *            the plot title (null if no plot should be displayed)
	 * @param histogramBins
	 * @param logFitParameters
	 *            Record the fit parameters to the ImageJ log
	 * @param removeOutliers
	 *            The distribution is created using all values within 1.5x the inter-quartile range (IQR) of the data
	 * @return The average precision
	 */
public double calculateAveragePrecision(ArrayList<Molecule> molecules, String title, int histogramBins, boolean logFitParameters, boolean removeOutliers) {
    // Plot histogram of the precision
    float[] data = new float[molecules.size()];
    DescriptiveStatistics stats = new DescriptiveStatistics();
    double yMin = Double.NEGATIVE_INFINITY, yMax = 0;
    for (int i = 0; i < data.length; i++) {
        data[i] = (float) molecules.get(i).precision;
        stats.addValue(data[i]);
    }
    // Set the min and max y-values using 1.5 x IQR 
    if (removeOutliers) {
        double lower = stats.getPercentile(25);
        double upper = stats.getPercentile(75);
        if (Double.isNaN(lower) || Double.isNaN(upper)) {
            if (logFitParameters)
                Utils.log("Error computing IQR: %f - %f", lower, upper);
        } else {
            double iqr = upper - lower;
            yMin = FastMath.max(lower - iqr, stats.getMin());
            yMax = FastMath.min(upper + iqr, stats.getMax());
            if (logFitParameters)
                Utils.log("  Data range: %f - %f. Plotting 1.5x IQR: %f - %f", stats.getMin(), stats.getMax(), yMin, yMax);
        }
    }
    if (yMin == Double.NEGATIVE_INFINITY) {
        yMin = stats.getMin();
        yMax = stats.getMax();
        if (logFitParameters)
            Utils.log("  Data range: %f - %f", yMin, yMax);
    }
    float[][] hist = Utils.calcHistogram(data, yMin, yMax, histogramBins);
    Plot2 plot = null;
    if (title != null) {
        plot = new Plot2(title, "Precision", "Frequency");
        float[] xValues = hist[0];
        float[] yValues = hist[1];
        if (xValues.length > 0) {
            double xPadding = 0.05 * (xValues[xValues.length - 1] - xValues[0]);
            plot.setLimits(xValues[0] - xPadding, xValues[xValues.length - 1] + xPadding, 0, Maths.max(yValues) * 1.05);
        }
        plot.addPoints(xValues, yValues, Plot2.BAR);
        Utils.display(title, plot);
    }
    // Extract non-zero data
    float[] x = Arrays.copyOf(hist[0], hist[0].length);
    float[] y = hist[1];
    int count = 0;
    float dx = (x[1] - x[0]) * 0.5f;
    for (int i = 0; i < y.length; i++) if (y[i] > 0) {
        x[count] = x[i] + dx;
        y[count] = y[i];
        count++;
    }
    x = Arrays.copyOf(x, count);
    y = Arrays.copyOf(y, count);
    // Sense check to fitted data. Get mean and SD of histogram
    double[] stats2 = Utils.getHistogramStatistics(x, y);
    double mean = stats2[0];
    if (logFitParameters)
        log("  Initial Statistics: %f +/- %f", stats2[0], stats2[1]);
    // Standard Gaussian fit
    double[] parameters = fitGaussian(x, y);
    if (parameters == null) {
        log("  Failed to fit initial Gaussian");
        return mean;
    }
    double newMean = parameters[1];
    double error = Math.abs(stats2[0] - newMean) / stats2[1];
    if (error > 3) {
        log("  Failed to fit Gaussian: %f standard deviations from histogram mean", error);
        return mean;
    }
    if (newMean < yMin || newMean > yMax) {
        log("  Failed to fit Gaussian: %f outside data range %f - %f", newMean, yMin, yMax);
        return mean;
    }
    mean = newMean;
    if (logFitParameters)
        log("  Initial Gaussian: %f @ %f +/- %f", parameters[0], parameters[1], parameters[2]);
    double[] initialSolution = new double[] { parameters[0], parameters[1], parameters[2], -1 };
    // Fit to a skewed Gaussian (or appropriate function)
    double[] skewParameters = fitSkewGaussian(x, y, initialSolution);
    if (skewParameters == null) {
        log("  Failed to fit Skewed Gaussian");
        return mean;
    }
    SkewNormalFunction sn = new SkewNormalFunction(skewParameters);
    if (logFitParameters)
        log("  Skewed Gaussian: %f @ %f +/- %f (a = %f) => %f +/- %f", skewParameters[0], skewParameters[1], skewParameters[2], skewParameters[3], sn.getMean(), Math.sqrt(sn.getVariance()));
    newMean = sn.getMean();
    error = Math.abs(stats2[0] - newMean) / stats2[1];
    if (error > 3) {
        log("  Failed to fit Skewed Gaussian: %f standard deviations from histogram mean", error);
        return mean;
    }
    if (newMean < yMin || newMean > yMax) {
        log("  Failed to fit Skewed Gaussian: %f outside data range %f - %f", newMean, yMin, yMax);
        return mean;
    }
    // Use original histogram x-axis to maintain all the bins
    if (plot != null) {
        x = hist[0];
        for (int i = 0; i < y.length; i++) x[i] += dx;
        plot.setColor(Color.red);
        addToPlot(plot, x, skewParameters, Plot2.LINE);
        plot.setColor(Color.black);
        Utils.display(title, plot);
    }
    // Return the average precision from the fitted curve
    return newMean;
}