MATLAB: Do I receive a “Value must be a handle” error when I modify the “XLabel”, “YLabel”, “ZLabel”, or “Title” property of an axes within MATLAB

MATLABsettitlexlabelylabelzlabel

When using the following command to set the "XLabel" property of the axes:

set(gca,'Xlabel','This is my label');

I receive an error message:

%BEGIN ERROR%%%

??? Error using ==> set

Value must be a handle.

%END ERROR%%%

Best Answer

Each of the "XLabel", "YLabel", "ZLabel", and "Title" properties of the axes is actually a handle to a text object.

It is recommended to use the XLABEL, YLABEL, ZLABEL, and TITLE functions directly. For example

xlabel('This is my label')

However, if you are required to use the SET function, you can use the following command:

set(get(gca,'XLabel'),'String','This is my label')

For more information about these properties of axes objects, see the following link:

https://www.mathworks.com/help/matlab/ref/matlab.graphics.axis.axes-properties.html

Related Solutions

MATLAB: How to make a legend that has both rows and columns

The ability to present a legend in the form of a matrix is added in MATLAB 9.4(R2018a).

You can specify Number of columns by using NumColums property of Legend object.

For details, please refer the documentation.

https://www.mathworks.com/help/matlab/ref/legend.html?lang=en&s_tid=gn_loc_drop#bt6r30y

In R2017b and previous release, it is not available as a built-in feature of MATLAB.

However, there exist several workarounds:

1) Use the GRIDLEGEND function from MATLAB Central:

http://www.mathworks.com/matlabcentral/fileexchange/29248-gridlegend-a-multi-column-format-for-legends

2) Use the COLUMNLEGEND function from MATLAB Central:

http://www.mathworks.com/matlabcentral/fileexchange/27389-columnlegend

3) Use the FLEXLEGEND function from MATLAB Central:

http://www.mathworks.com/matlabcentral/fileexchange/31092-legendflex-a-more-flexible-legend

4) Use the following code:

% Example data
xData = linspace(0,pi);
y1 = sin(xData);
y2 = cos(xData);
y3 = sin(xData.^2);
y4 = cos(xData.^2);
% Plot the first two sets of data
ph1(1) = plot(xData,y3,'-ko','DisplayName','Y3 Legend Text');
hold on
ph1(2) = plot(xData,y4,'-bs','DisplayName','Y4 Legend Text');
% Create the first legend
lh1 = legend(ph1,'Location','NorthOutside','Orientation','horizontal');
lh1_position = get(lh1,'Position');
% Now set any axis properties that you want (Font, Ticks, etc)
fontSize = 16;
xlimits = [0,pi];
ylimits = [-1, 1];
xticks  = [0, pi/2, pi];
yticks  = [-1, 0, 1];
xTickLabels = {'0', 'pi/2', 'pi'};
set(gca,'XLim',xlimits,'YLim',ylimits,'FontSize',fontSize,'XTick',xticks,'YTick',yticks,'xTickLabel',xTickLabels);
% Name the first axis ax1 and create a second axis on top of the first
ax1 = gca;
ax2 = axes('Position',get(ax1,'Position'));
% Plot the second two sets of data on ax2
ph2(1) = plot(xData,y1,'-rd','DisplayName','Y1 Legend Text','Parent',ax2);
hold on
ph2(2) = plot(xData,y2,'-g^','DisplayName','Y2 Legend Text','Parent',ax2);
% Again set any axis properties that you want (Font, Ticks, etc) to make sure that the Legend fonts are the same
set(ax2,'XLim',xlimits,'YLim',ylimits,'FontSize',fontSize,'XTick',xticks,'YTick',yticks);
% Now, link the first axis to the second and make the second invisible
linkaxes([ax1 ax2],'xy');
set(ax2,'Color','none','XTick',[],'YTick',[],'Box','off');
% Now make the second legend just above the first
lh2 = legend(ax2,ph2,'Orientation','horizontal');
lh2_position = lh1_position;
lh2_position(2) = lh1_position(2)+1.25*lh2_position(4);
set(lh2,'Position',lh2_position);

MATLAB: How to change the font size of text in a figure

To change the font size, set the “FontSize” property for the axes. Since many plotting functions reset axes properties, including the font size, set the "FontSize" property after plotting.

For example, the code below sets the font size to 16 points. The tick labels use the specified font size. The title and axis labels use a slightly larger font size.

   plot(1:10) 
   title('My title') 
   xlabel('My label') 
   ax = gca; 
   ax.FontSize = 16;

Alternatively, if you want more individual control over the font size, you can specify the “FontSize” property as name-value pair to the “title” and “xlabel” functions, as in the example below.

   plot(1:10) 
   title('My title','FontSize',16) 
   xlabel('My label','FontSize',10)

Best Answer

Related Solutions

MATLAB: How to make a legend that has both rows and columns

MATLAB: How to change the font size of text in a figure

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