Plot legend title - Undocumented Matlab (2024)

11 Responses

1. 

   FredApril 1, 2015 at 15:34Reply

   The workaround I use is to plot the first point of my first line with ‘w.’, then include it as the first handle in my call to legend, with its text as the desired legend title. In this example the handles for the legend are left implicit.

   figurehold on;plot(r(1),'w.');plot(r);legend('Traces','First','Second')

   Cheers,

2. 

   MartinApril 1, 2015 at 15:44Reply

   I haven’t really tested for any undesired side effects, but I have the feeling that this qualifies as a more elegant solution:

   hLegend = legend(...)hlt = text(... 'Parent', hLegend.DecorationContainer, ... 'String', 'Title', ... 'HorizontalAlignment', 'center', ... 'VerticalAlignment', 'bottom', ... 'Position', [0.5, 1.05, 0], ... 'Units', 'normalized');

   The title appears to stay attached to the legend and the Parent property of the text object even reports the legend object as its parent:

   hLegend.Location = 'southwest'; % Test the title's attachmenthlt.Parent % Returns hLegend

   I tested this with R2015a. The DecorationContainer was simply the first in a rather long list of properties that sounded like it could be useful.

   See Also

   Add Legend to Graph - MATLAB & Simulink

• 

  Yair AltmanApril 1, 2015 at 16:42Reply

  @Martin – thanks! this is indeed more elegant. I tried setting a text object’s Parent directly to the legend and received an error (“Text cannot be a child of Legend”); I then tried to set the DecorationContainer’s title property and got another error (since it’s not an axes and has no such property); but I didn’t think to simply try what you did, which is a variant of my failed attempts…

  I guess it shows us that we should never give up hope, maybe just take a step back and rethink about the problem.

  Thanks again!

• 

  MartinApril 3, 2015 at 08:36Reply

  @Yair – thanks for improving my comment and fixing the minor error I included! I see you read those comments very carefully. 🙂

  R2015a made it easier to to explore HG2 (and the many undocumented properties/methods of the related classes) by adding the new (and hidden) Type property to the meta.property class and the InputTypes and OutputTypes properties to the the meta.method class. For example:

  mc = ?matlab.graphics.axis.Axes;mc.PropertyList(1).Name % Cameramc.PropertyList(1).Type % matlab.graphics.axis.camera.Cameramc.MethodList(49).Name % addlistenermc.MethodList(49).InputNames % [sources, propertyname, eventname, callback]mc.MethodList(49).InputTypes % [handle, asciiString, char vector, function_handle scalar]

  Knowing the type of a property can be especially helpful to find out what can be assigned to it. Sometimes one even gets a list of valid values (e.g. the CameraMode property of the above Axes class).

• 

  Yair AltmanApril 8, 2015 at 13:15

  @Martin – thanks, interesting. I have a hunch that this is related to the undocumented mechanism of setting class-property types using the so-called “@-filter”:

  properties Name@char = 'abc' Width@double = 10end

  Unfortunately, I tried this @-filter on method input/output args and it croacks. So either it’s not implemented yet, or MathWorks may have changed the syntax, or maybe I’m just misreading the situation…

• 

  MartinApril 8, 2015 at 23:29Reply

  @Yair – Yes, I’d say this is related. Obviously, there is internal support for data types for both properties and function/method arguments. But only the former got the (undocumented) @-syntax in the MATLAB language, as described by your linked post. The latter seems to be reserved to built-in functions and methods of built-in classes, that are implemented in C++ and are thus not restricted by what is exposed to the MATLAB language. (I also tried and failed to find a syntax that would work for arguments.)

  I wonder why MathWorks decided to expose only “half” of this data type feature to MATLAB programmers. And I wonder why they added “full” support for querying this information directly from MATLAB in R2015a. (Not that I’m complaining, it provides interesting insights.)

  Finally, I wonder what those data types really are. (I think we had something similar in the UDD class system.) They are not real classes, as can be seen in many instances in HG2. But classes can be used as data types. Will data types be fully exposed to the MATLAB language? Will we be able to create and use custom data types in the future?

hLegend = legend();hLegend.Title.String = 'My Legend Title'.

• 

  Yair AltmanJune 25, 2017 at 00:54Reply

  ???

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disp(sum(a))
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