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Chart Class with Variable Number of Lines

This example shows how to define a class of charts that can display any number of lines based on the size of the user's data. The chart displays as many lines as there are columns in theYDatamatrix. For each line, the chart calculates the local extrema and indicates their locations with circular markers. The following code demonstrates how to:

  • Define two properties calledPlotLineArrayandExtremaArraythat store the objects for the lines and the markers, respectively.

  • Implement anupdatemethod that replaces the contents of thePlotLineArrayandExtremaArrayproperties with the new objects. Because this method executes all the plotting and configuration commands, thesetupmethod is empty. This is a simple way to create any number of lines. To learn how to create this chart more efficiently, by reusing existing line objects, seeOptimized Chart Class for Displaying Variable Number of Lines.

To define the class, copy this code into the editor and save it with the nameLocalExtremaChart.min a writable folder.

classdefLocalExtremaChart < matlab.graphics.chartcontainer.ChartContainer% c = LocalExtremaChart('XData',X,'YData',Y,Name,Value,...)% plots one line with markers at local extrema for every column of matrix Y.% You can also specify the additonal name-value arguments, 'MarkerColor'% and 'MarkerSize'.propertiesXData(1,:) double= NaN YData(:,:) double= NaN MarkerColor{validatecolor}= [1 0 0] MarkerSize(1,1) double= 5endproperties(Access = private,Transient,NonCopyable) PlotLineArray(:,1) matlab.graphics.chart.primitive.LineExtremaArray(:,1) matlab.graphics.chart.primitive.Lineendmethods(Access = protected)functionsetup(~)endfunctionupdate(obj)% get the axesax =木屐xes(obj);% Plot Lines and the local extremaobj.PlotLineArray = plot(ax,obj.XData,obj.YData); hold(ax,'on')% Replicate x-coordinate vectors to match size of YDatanewx = repmat(obj.XData(:),1,size(obj.YData,2));% Find local minima and maxima and plot markerstfmin = islocalmin(obj.YData,1); tfmax = islocalmax(obj.YData,1); obj.ExtremaArray = plot(ax,newx(tfmin),obj.YData(tfmin),'o',...newx(tfmax),obj.YData(tfmax),'o',...'MarkerEdgeColor','none',...'MarkerFaceColor',obj.MarkerColor,...'MarkerSize',obj.MarkerSize); hold(ax,'off')endendend

After saving the class file, you can create an instance of the chart. For example:

x = linspace(0,3); y1 = cos(5*x)./(1+x.^2); y2 = -cos(5*x)./(1+x.^3); y3 = sin(x)./2; y = [y1' y2' y3']; c = LocalExtremaChart(“XData”,x,'YData',y);

Change the marker size to8.

c.MarkerSize = 8;

See Also

Classes

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