Last week, Scott Hirsh, Matlab’s lead product manager, posted an article ^[1] about Matlab’s redesigned plot catalog. In that post, Scott mentioned the internal deliberations about whether the plot catalog was needed at all. He explained how the final decision was to keep and enhance the catalog, rather than remove it, based on user feedback that the catalog is in fact useful, its main benefit being the fact that it is large and easy to use.
I posted a short comment ^[2] mentioning my experience of using the catalog programmatically as another use-case that might be taken into consideration. Today, I would like to expand that short comment and explain how built-in plot-selection components can be used in our Matlab GUI programs.

Built-in plot selection components

PlotTypeCombo is a plot-function selector is that is one of my personal favorite controls for embedding in a Matlab application:

% Present the PlotCombo control
import com.mathworks.mlwidgets.graphics.*
jPlotCombo = PlotTypeCombo;
pos = [100,100,170,50];
[jhPlotCombo,hPanel] = javacomponent(jPlotCombo,pos,gcf);
set(jhPlotCombo,'ActionPerformedCallback',@myCBFcn);
% Callback function to process PlotCombo selections
function myCBFcn(jObject,jEventData)
   newPlotFunc = jObject.getSelectedItem.getName.char;
   %Now do something useful with the selected function
end  % myCBFcn

PlotCatalog is a dialog window that presents the plot functions catalog:

com.mathworks.mlwidgets.graphics.PlotCatalog.getInstance.show

  

Usage example

For one application that I developed for a client, I implemented a dynamic report page that enables users to select the plotting function using a PlotTypeCombo. When users select a non-default function (e.g. stairs or loglog), that function is automatically added to the combo-box for possible future reuse. I implemented this as follows:

% Add the specified plotFunc to a PlotTypeCombo control
function updatePlotCombo(plotCombo, plotFunc)
   % Convert plotFunc (a Matlab string) into a Java PlotSignature
   import com.mathworks.mlwidgets.graphics.*
   plotSig = PlotMetadata.getPlotSignature(plotFunc);
   % Get the list of all existing plot types in the combo box
   existingPlotTypes = {};
   for plotIdx = 0 : plotCombo.ItemCount-1
      nextItem = plotCombo.getItemAt(plotIdx);
      if isjava(nextItem)
         nextItem = char(nextItem.getName);
      end
      existingPlotTypes = [existingPlotTypes, nextItem];
   end
   % If the new plotType is NOT already in the list
   if isempty(strmatch(plotType,existingPlotTypes,'exact'))
      % Add the new plotType to the list just prior to the end,
      % so that "More plots..." will always be last
      plotCombo.insertItemAt(plotSig,plotCombo.ItemCount-1);
   end
   % Set the currently-selected item to be the requested plotType
   % Note: temporarily disable callbacks to prevent involuntary action
   plotCombo.ActionPerformedCallback = [];
   plotCombo.setSelectedItem(plotSig);
   plotCombo.ActionPerformedCallback = @myCBFcn;  % selection callback
end  % updatePlotCombo

Usage of this function would then be as simple as invoking the updatePlotCombo() function:

updatePlotCombo(jhPlotCombo,'stairs');

Plot signatures

The astute reader will have noticed from the updatePlotCombo() function above, that the PlotTypeCombo items are plot-signature objects. Different plot functions expect a different set of input arguments (a.k.a. signature). This information is kept and can be queried from the PlotMetadata class:

>> com.mathworks.mlwidgets.graphics.PlotMetadata.listAllSignatures
ans =
[area, bar, bar (stacked), barh (stacked), barh, comet, compass, errorbar,
 feather, loglog, plot, plot N series, plot N series against T, plot3, plotmatrix, plotyy,
 polar, quiver, quiver3, ribbon, scatter, scatter3, semilogx, semilogy,
 stairs, stem, stem3, null, contour, contour3, contourf, image,
 imagesc, mesh, meshc, meshz, pcolor, plot against first column, surf, surfc,
 surfl, waterfall, null, contour, contour3, contourf, image, imagesc,
 mesh, meshc, meshz, pcolor, plot against first column, surf, surfc, surfl, waterfall]
>> plotFunc = 'surf';  % for example
>> plotSig = PlotMetadata.getPlotSignature(plotFunc);
>> args = cell(plotSig.getArgs)';
args =
    [1x1 com.mathworks.mlwidgets.graphics.PlotArgDescriptor]
    [1x1 com.mathworks.mlwidgets.graphics.PlotArgDescriptor]
    [1x1 com.mathworks.mlwidgets.graphics.PlotArgDescriptor]
    [1x1 com.mathworks.mlwidgets.graphics.PlotArgDescriptor]
>> argsStruct = [];  % initialize
>> for argsIdx = 1 : length(args)
      argsStruct(argsIdx).axis = char(args{argsIdx}.getAxis);
      argsStruct(argsIdx).name = char(args{argsIdx}.getName);
      argsStruct(argsIdx).label = char(args{argsIdx}.getLabel);
      argsStruct(argsIdx).dims = args{argsIdx}.getNumDimensions;
      argsStruct(argsIdx).reqObj = args{argsIdx}.getRequired;
      req = argsStruct(argsIdx).reqObj;
      argsStruct(argsIdx).requiredFlag = req.equals(req.REQUIRED);
   end
>> disp(argsStruct(1))			% Info about the first input argument
            axis: 'X'
            name: 'X'
           label: 'X Data Source'
            dims: [2x1 int32]
          reqObj: [1x1 com.mathworks.mlwidgets.graphics.PlotArgDescriptor$RequiredType]
    requiredFlag: 0
>> disp({argsStruct.axis})		% axis info of all input arguments
    'X'    'Y'    'Z'    ''
>> disp({argsStruct.name})		% name of all input arguments
    'X'    'Y'    'Z'    'C'
>> disp({argsStruct.label})	% data label of all input arguments
    'X Data Source'    'Y Data Source'    'Z Data Source'    'Color'
>> disp({argsStruct.dims})		% dimensionality of all input args
    [2x1 int32]    [2x1 int32]    [2]    [2]
>> disp({argsStruct.requiredFlag})	% is any input arg mandatory?
    [0]    [0]    [1]    [0]

This signature data can be queried for each separate plot type. In fact, I use this mechanism above so that whenever the user changes the plot-type in the PlotTypeCombo, the usage label text beneath the combo-box is updated with the specific plot’s signature information:

5 Comments To "Plot-type selection components"

#1 Comment By Amjad Elshenawy On June 26, 2011 @ 04:33

#2 Comment By Yair Altman On June 26, 2011 @ 06:48

#3 Pingback By Specialized Matlab plots | Undocumented Matlab On April 11, 2012 @ 10:27

#4 Comment By Brad Stiritz On May 15, 2013 @ 16:13

#5 Comment By Yair Altman On May 28, 2013 @ 17:31

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