Can you create string variables to use in plots that use LaTeX?

Hello,

I have a few graphs that I plot. I want to change the name of the legend entries / the DisplayName of the graph in one location.

So I set up string variables:

namePlot1 = "First measurement";

namePlot2 = "Second measurement";

Later during plotting I use that variable for the DisplayName.

scatter(plotData_X,plotData_Y,"DisplayName",namePlot1);

Now I want to use LaTeX expressions in some of the texts. More specificaly, the average x with a line above it.

'$\bar{x}$'

To display LaTeX text, you have to set 'Interpreter','latex'. But from what I understood so far, you use that inside a plot or legend command.

Is there a way to add Latex symbols to a variable and then use that variable to change the names of plot X/YLabel Strings and plot DisplayNames?

Answer 1

[Hassaan]

% Define your LaTeX string variables for plot names
namePlot1 = '$\bar{x}$ First measurement';
namePlot2 = '$\bar{y}$ Second measurement';

% Some example data for the scatter plots
plotData_X1 = rand(10,1); % Random data for the first plot
plotData_Y1 = rand(10,1);
plotData_X2 = rand(10,1); % Random data for the second plot
plotData_Y2 = rand(10,1);

% Create the first scatter plot and use the LaTeX string for DisplayName
scatter(plotData_X1, plotData_Y1, 'DisplayName', namePlot1);

% Hold the current figure so that the next plot doesn't overwrite it
hold on;

% Create the second scatter plot and use the LaTeX string for DisplayName
scatter(plotData_X2, plotData_Y2, 'DisplayName', namePlot2);

% Add legend to the plot with LaTeX interpreter
legend('Interpreter', 'latex');

% Add labels to the axes with LaTeX interpreter
xlabel('X-axis Label', 'Interpreter', 'latex');
ylabel('Y-axis Label', 'Interpreter', 'latex');

% Set title with LaTeX interpreter
title('Comparison of Measurements', 'Interpreter', 'latex');

% Release the hold on the figure
hold off;

This script will create a figure with two scatter plots, each with a display name that includes a LaTeX-formatted bar over the variable names ˉxˉ and ˉyˉ​. The legend, axis labels, and title will also be able to render LaTeX formatted text since we have specified the 'Interpreter' as 'latex'.

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[Daniel Neyers]

Thank you for your answer. It works fine with the plot legends.

Two followup questions:

1:

I only use LaTeX notation with some plot names, not with all.

So I have namePlot1 and namePlot2 with LaTex in them, but a namePlot3 without aswell.

namePlot1 = '$\bar{x}$ First measurement';

namePlot2 = '$\bar{y}$ Second measurement';

namePlot3 = 'Reference value';

Due to that I have two different fonts in the graph. Is there a way to match the two without too much hassle? (I.e. dealing with font settings for the text.)

Or how do I make all text use LaTeX notation, even if there is no sign in it?

2: I used:

legend('Interpreter', 'latex');

% Change legend parameters

legend_par = legend;

legend_par.FontSize = 8;

legend_par.Location = "northwest";

Then to manipulate the axis I used:

ax = gca;

ax.XAxis.Limits = [0 x_max];

ax.YAxis.Limits = [0 y_max];

ax.Layer = "top";

ax.FontSize = 8;

ax.XLabel.FontSize = 8;

ax.XLabel.String = stringX_AxisName;

So it is different to the way you added the labels. Is it possible to apply that to my variant with the gca variable "ax"?

Or can I mix your notation with mine and replace the "ax.XLabel.String" commands?

[Hassaan]

@Daniel Neyers

When you mix text with and without LaTeX in MATLAB figures, MATLAB will render the LaTeX text using the TeX markup, and the plain text using the default font, which might lead to inconsistencies in font type and size. Not recommended.

Yes, you can use the gca handle to set properties of the axes, including the labels, and you can specify the interpreter for each label individually. Here is how you can do it:

% Set legend parameters
legend_par = legend;
legend_par.Interpreter = 'latex'; % Set the interpreter for legend text to LaTeX
legend_par.FontSize = 8;
legend_par.Location = "northwest";
% Manipulate the axis using gca
ax = gca;
ax.XAxis.Limits = [0 x_max];
ax.YAxis.Limits = [0 y_max];
ax.Layer = "top";
ax.FontSize = 8;
% Set the axis labels using LaTeX interpreter
ax.XLabel.Interpreter = 'latex';
ax.XLabel.String = ['$' stringX_AxisName '$']; % Wrap the string in $ to use LaTeX
ax.XLabel.FontSize = 8;
% Do the same for YLabel if needed
ax.YLabel.Interpreter = 'latex';
ax.YLabel.String = ['$' stringY_AxisName '$'];
ax.YLabel.FontSize = 8;

By wrapping the string for the axis label in $ signs, you are telling MATLAB to interpret this text as LaTeX, even if it doesn't contain any LaTeX commands. This will apply the LaTeX interpreter to the axis labels as well and maintain consistency with the legend text.

if you want more control over the placement of labels in your MATLAB figures, you can indeed use the text function instead of setting the XLabel and YLabel properties. The text function allows you to specify the exact location where you want the text to appear.

% Define your axis limits
x_max = 10; % Example value
y_max = 10; % Example value

% Plot your data
% ... (Your plotting code)

% Set the properties of the axes
ax = gca;
ax.XAxis.Limits = [0 x_max];
ax.YAxis.Limits = [0 y_max];
ax.Layer = "top";
ax.FontSize = 8;

% Place a LaTeX formatted text label at a desired location on the plot
% The coordinates here (x, y) should be chosen based on where you want the label to appear
text('Units', 'normalized', 'Position', [0.5, -0.1], 'String', '$\bar{x}$ Axis Label', ...
     'Interpreter', 'latex', 'FontSize', 8, 'HorizontalAlignment', 'center');

text('Units', 'normalized', 'Position', [-0.1, 0.5], 'String', '$\bar{y}$ Axis Label', ...
     'Interpreter', 'latex', 'FontSize', 8, 'HorizontalAlignment', 'center', ...
     'Rotation', 90); % The rotation property will align the y-axis label vertically

% Continue with the rest of your plotting code

• The Units property is set to 'normalized' which means the position will be relative to the figure's width and height. Values of 0 are at the origin and 1 at the opposite side of the figure.
• The Position property specifies the location of the text. For the x-axis label, a position below the axis is chosen by using a small negative value. For the y-axis label, a position to the left of the axis is chosen.
• The String property contains the label text with LaTeX formatting.
• The Interpreter property is set to 'latex' to render the text with LaTeX.
• The HorizontalAlignment property is used to align the

text centered relative to the specified position.

• The Rotation property for the y-axis label is used to rotate the text so that it aligns vertically as is standard for y-axis labels.

By using the text function, you can place your labels at any arbitrary position on the figure. This is particularly useful when the default label positions are not suitable or if you want to add additional text annotations within the figure.

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If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.

[Daniel Neyers]

Thank you for the detailed answer. Sadly something is not working correctly.

Let's see. Excuse the variable names, I will keep then in my native language this time.

% Plotitel

plotTitel = "Hallway";

plotUntertitel = "Experiment 1";

% Name for axis

beschriftung_X_Achse = "Messposition";

beschriftung_Y_Achse = "Distanz $\it{d}$ in cm";

% Name for Legend

nameIstPos1 = "Height 1,5m";

nameSollPos1 = "Soll-Pos. 1";

nameAverage1 = "Average $\bar{d}$ (T 1,5m)";

% plot graphs

clf

figure(1)

hold on

scatter(plotData_X,plotData_Y,20,farbeIstPos1,"x","LineWidth",0.7,"DisplayName",nameIstPos1);

plot(nan,nan,"Color",farbeIstPos1,"LineWidth",1.0,"DisplayName",nameAverage1);

% Change legend parameters

legend_par = legend;

legend_par.Interpreter = 'latex';

legend_par.FontSize = 8;

legend_par.Location = "northwest";

%x_max=31.30;

y_max=300;

ax = gca;

%ax.XAxis.Limits = [0 x_max];

ax.YAxis.Limits = [0 y_max];

ax.Layer = "top";

%set(ax,"XTick",0:5:x_max);

ax.FontSize = 8;

ax.XLabel.Interpreter = 'latex';

ax.XLabel.String = ['$' beschriftung_X_Achse '$'];

ax.XLabel.FontSize = 8;

set(ax,"YTick",0:20:y_max);

ax.YLabel.Interpreter = 'latex';

ax.YLabel.String = ['$' beschriftung_Y_Achse '$'];

ax.YLabel.FontSize = 8;

% Plot_Titel und Plot_Subtitle

[p_title,p_subtitle]=title(plotTitel,plotUntertitel);

p_title.FontSize = 9;

p_subtitle.FontSize = 8;

I hope I didn't miss anything. Now I get the following effects and warnings:

Warning: Error updating Text.

String scalar or character vector must have valid interpreter syntax:

$

Messposition

$

This one is for the x-axis.

There are warnings and fallbacks for:

beschriftung_X_Achse

beschriftung_Y_Achse

nameIstPos1 % used in scatter plot

nameSollPos1 wasn't used in this plot, but will likely be identical.

So:

LaTeX for plot command in legend works.

LaTeX for scatterplot in legend does not work.

Labels for Axis do not work.

Do you have any idea what I missed?

[Hassaan]

@Daniel Neyers

1. LaTeX in Axis Labels: When using LaTeX, you don't need to wrap the entire string in $ signs unless the entire string is a LaTeX expression. Try removing the $ signs around your axis label strings.
2. LaTeX in Legend Entries: For the legend entries, MATLAB should interpret the LaTeX correctly as long as the Interpreter is set to 'latex'. Ensure that your legend entry strings are valid LaTeX strings.

% Axis Labels
ax.XLabel.Interpreter = 'latex';
ax.XLabel.String = beschriftung_X_Achse; % No need for $ signs
ax.XLabel.FontSize = 8;

ax.YLabel.Interpreter = 'latex';
ax.YLabel.String = beschriftung_Y_Achse; % LaTeX will be interpreted correctly
ax.YLabel.FontSize = 8;

% Legend Entries
% Ensure that nameIstPos1, nameSollPos1, nameAverage1 are valid LaTeX strings
scatter(plotData_X, plotData_Y, 20, farbeIstPos1, "x", "LineWidth", 0.7, "DisplayName", nameIstPos1);
plot(nan, nan, "Color", farbeIstPos1, "LineWidth", 1.0, "DisplayName", nameAverage1);

% Change legend parameters
legend_par = legend;
legend_par.Interpreter = 'latex'; % This will interpret the LaTeX in legend entries
legend_par.FontSize = 8;
legend_par.Location = "northwest";

Dummy Example

% Dummy data for demonstration
plotData_X = rand(50, 1) * 20; % Random X data between 0 and 20
plotData_Y = rand(50, 1) * 300; % Random Y data between 0 and 300
farbeIstPos1 = [0, 0.4470, 0.7410]; % A default MATLAB color

% Plotitel
plotTitel = "Hallway";
plotUntertitel = "Experiment 1";

% Name for axis
beschriftung_X_Achse = "Messposition";
beschriftung_Y_Achse = "Distanz $\it{d}$ in cm";

% Name for Legend
nameIstPos1 = "Height 1,5m";
nameSollPos1 = "Soll-Pos. 1";
nameAverage1 = "Average $\bar{d}$ (T 1,5m)";

% plot graphs
clf;
figure(1);
hold on;
scatter(plotData_X, plotData_Y, 20, farbeIstPos1, "x", "LineWidth", 0.7, "DisplayName", nameIstPos1);
plot(nan, nan, "Color", farbeIstPos1, "LineWidth", 1.0, "DisplayName", nameAverage1);

% Change legend parameters
legend_par = legend;
legend_par.Interpreter = 'latex';
legend_par.FontSize = 8;
legend_par.Location = "northwest";

% Axis settings
y_max = 300;
ax = gca;

%ax.XAxis.Limits = [0 x_max];
ax.YAxis.Limits = [0 y_max];
ax.Layer = "top";

%set(ax,"XTick",0:5:x_max);
ax.FontSize = 8;
ax.XLabel.Interpreter = 'latex';
ax.XLabel.String = beschriftung_X_Achse;
ax.XLabel.FontSize = 8;
set(ax, "YTick", 0:20:y_max);
ax.YLabel.Interpreter = 'latex';
ax.YLabel.String = beschriftung_Y_Achse;
ax.YLabel.FontSize = 8;

% Plot Title and Subtitle
[p_title, p_subtitle] = title(plotTitel, plotUntertitel);
p_title.FontSize = 9;
p_subtitle.FontSize = 8;

------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.

[Daniel Neyers]

I see, I was a bit confused with the

ax.XLabel.String = ['$' stringX_AxisName '$']; % Wrap the string in $ to use LaTeX

from your previous response.

It looks like it mostly works, except for "nameIstPos1". What happens if you add a $\bar{d}$ to the nameIstPos1 string? Does it get converted to LaTeX correctly? By the look of your font it would.

Oh my godness. I got completely confused because:

nameIstPos2 = "Höhe 1,0m $\bar{d}$";

Outputs "Höhe 1,0m $\bar{d}$" in standard font and throws the warning:

"String scalar or character vector must have valid interpreter syntax: Transponderhöhe 2,0m"

Compared to that,

nameIstPos1 = "Height 1,5m $\bar{d}$";

works perfectly fine. Which I didn't try, since I only used the word "Höhe" and was completely confused. It worked for the regular plot, but not for the scatter plot.

Now I know why it threw the warning: It can not interpret the letter ö. Wow, what a rollercoaster.

Now I only have to figure out if and how I can insert the letters ä ö and ü in text strings.

Edit:

{\"a} = ä

{\"o} = ö

{\"u} = ü

Works:

'H{\"o}he 1,5m'

Does not work:

"H{\"o}he 1,5m"

Looks like I should stop using double quotation marks { " } to mark strings and use single ones { ' } instead.

Fascinating how much headache the small nuances in language differences can make. I assume you would have spotted that hours ago if I didn't forget to include that warning message.

Thank you for all the help @Muhammad Hassaan Shah.

Edit 2: You don't happen to have expertise with exporting figures in export_fig, do you? :-)

[Hassaan]

@Daniel Neyers I do actually :-)

[Daniel Neyers]

@Muhammad Hassaan Shah Then may I refer you to my rather text heavy question over here?

https://www.mathworks.com/matlabcentral/answers/2069721-how-to-prevent-export_fig-plot-background-images-to-have-a-low-resolution

Long story short:

I upload a high resolution background image which shows up fine in the Matlab view. Once I export it with

export_fig(export_figname, '-png','-a1', '-native');

the background itself turns into a blur. As if it got downscaled and then upscaled again.

[Hassaan]

@Daniel Neyers That's indeed some serious stuff :-) :-). I will see what can be done. Thank you.