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Optimized Chart Class for Displaying Variable Number of Lines

This example shows how to optimize a chart class for displaying a variable number of lines. It reuses existing line objects, which can improve the performance of the chart, especially if the number of lines does not change frequently. For a simpler version of this chart without the optimization, seeChart Class with Variable Number of Lines.

The chart displays as many lines as there are columns in theYDatamatrix, with circular markers at the local extrema. The following code demonstrates how to:

  • Define two properties calledPlotlineArray.和ExtremaLinethat store the objects for the lines and the markers, respectively.

  • Implement asetupmethod that initializes theExtremaLine目的。

  • Implement anupdatemethod that gets the size of thePlotlineArray., and then adds or subtracts objects from that array according to the number of columns inYData.

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

classdefOptimLocalExtremaChart < matlab.graphics.chartcontainer.ChartContainer% c = OptimLocalExtremaChart('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'.特性XData(:,1) double= NaN YData(:,:) double= NaN MarkerColor{validatecolor}= [1 0 0] MarkerSize（1,1）双= 5end特性(Access = private,Transient,NonCopyable) PlotLineArray(:,1) matlab.graphics.chart.primitive.LineExtremaLine(:,1) matlab.graphics.chart.primitive.Lineendmethods(Access = protected)functionsetup(obj) obj.ExtremaLine = matlab.graphics.chart.primitive.Line(...'Parent', obj.getAxes(),'Marker','o',...'MarkerEdgeColor','none','LineStyle',' none');endfunction更新（obj）% Get the axesax =木屐xes(obj);% Create extra lines as neededp = obj.PlotLineArray; nPlotLinesNeeded = size(obj.YData, 2); nPlotLinesHave = numel(p);forn = nPlotLinesHave+1:nPlotLinesNeeded p(n) = matlab.graphics.chart.primitive.Line('Parent', ax,...'SeriesIndex'，n，'LineWidth', 2);end% Update the linesforn = 1：nplotlinesneeded p（n）.xdata = obj.xdata;p（n）.ydata = obj.ydata（：，n）;end% Delete unneeded linesdelete(p((nPlotLinesNeeded+1):numel(p))) obj.PlotLineArray = p(1:nPlotLinesNeeded);% 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.extremaline.xdata = [newx（tfmin）;newx（tfmax）];obj.extremaline.ydata = [obj.ydata（tfmin）;obj.ydata（tfmax）];obj.extremaline.markerfacecolor = obj.markercolor;obj.extremaline.markersize = obj.markersize;% Make sure the extrema are on topuistack(obj.ExtremaLine,'top');endendend

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

x = linspace(0,2)'; y = cos(5*x)./(1+x.^2); c = OptimLocalExtremaChart(“XData”，X，'YData',y);

Now, create afor循环在每次迭代时添加到绘图的附加线。图表对象保留所有现有行，并为每个添加一个addital行i.

fori=1:10 y = cos(5*x+i)./(1+x.^2); c.YData = [c.YData y];end

See Also

Classes

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