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Set up instance of chart container subclass

Since R2019b




setup(obj) sets the initial state of the chart. It executes once when the chart object is created. Any property values passed as name-value pair arguments to the chart's constructor method are assigned after the setup method executes.

Define this method to execute initialization code for each new instance of your class. For example, you can use this method to create the underlying graphics objects and set initial property values on those objects.

Input Arguments

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Object of the class that inherits from the base class.



To learn about attributes of methods, see Method Attributes.


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Define a class called SmoothPlot that plots a set of data using a dotted blue line with a smoothed version of the line.

To define the class, create a file called SmoothPlot.m that contains the following class definition with these features:

  • XData and YData public properties that store the x- and y-coordinate data for the original line.

  • SmoothColor and SmoothWidth public properties that control the color and width of the smooth line.

  • OriginalLine and SmoothLine private properties that store the Line objects for original and smoothed data.

  • A setup method that initializes OriginalLine and SmoothLine.

  • An update method that updates the plot when the user changes the value of a property.

  • A createSmoothData method that calculates a smoothed version of YData.

classdef SmoothPlot <
        XData (1,:) double = NaN
        YData (1,:) double = NaN
        SmoothColor (1,3) double {mustBeGreaterThanOrEqual(SmoothColor,0),...
            mustBeLessThanOrEqual(SmoothColor,1)} = [0.9290 0.6940 0.1250]
        SmoothWidth (1,1) double = 2
    properties(Access = private,Transient,NonCopyable)
        OriginalLine (1,1)
        SmoothLine (1,1)
    methods(Access = protected)
        function setup(obj)
            % Create the axes
            ax = getAxes(obj);
            % Create the original and smooth lines
            obj.OriginalLine = plot(ax,NaN,NaN,'LineStyle',':');
            obj.SmoothLine = plot(ax,NaN,NaN);
        function update(obj)
            % Update line data
            obj.OriginalLine.XData = obj.XData;
            obj.OriginalLine.YData = obj.YData;
            obj.SmoothLine.XData = obj.XData;
            obj.SmoothLine.YData = createSmoothData(obj);
            % Update line color and width
            obj.SmoothLine.Color = obj.SmoothColor;
            obj.SmoothLine.LineWidth = obj.SmoothWidth;
        function sm = createSmoothData(obj)
            % Calculate smoothed data
            v = ones(1,10)*0.1;
            sm = conv(obj.YData,v,'same');

Next, create a pair of x and y vectors. Plot x and y by calling the SmoothPlot constructor method, which is provided by the ChartContainer class. Specify the 'XData' and 'YData' name-value pair arguments and return the object as c.

x = 1:1:100;
y = 10*sin(x./5) + 8*sin(10.*x + 0.5);
c = SmoothPlot('XData',x,'YData',y);

Use c to change the color of the smooth line to red.

c.SmoothColor = [1 0 0];


Avoid calling drawnow within the setup and update methods of your chart class. Calling drawnow in the setup and update methods can cause extraneous updates within your chart, leading to visual flickering and extraneous updates to objects outside your chart, which will negatively impact performance.

Version History

Introduced in R2019b

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