MATLAB: How to insert variable name into graph title

fprintfprintvariable name

Dear All,

I would like to ask how I would print the variable name into the graph title

example:

function abc(varname)
.
.
.
title('Graph of 'insert varname here'')

thank you

Best Answer

The name of the variable should not matter. Not that it is "varname" in every case here. But the name might be different in the caller. Nevertheless, relying on the name is a pitfall. Better create a specific variable, which carries the name:

data = 1:10;
name = 'My Data';
function abc(data, name)
plot(data);
title(sprintf('Graph of %s', name));

But beside this general advice to separate the program and the data strictly, there is a dirty command to do this:

function abc(data)
name = inputname;
if isempty(name)
  name = 'unknown';
end
plot(data);
title(sprintf('Graph of %s', name));

The test for the empyt name is required when you call your function e.g. by:

abc(1:10)

Then there is no name, because the data are created dynamically. The same problem:

x = 1:10;
abs(x(2:7))

I'm not sure if inputname works here. Therefore I would not play with such meta-programming techniques, when providing a specified name as additional variable is such dry and clean.

Perhaps you can use a struct:

data.value = 1:10;
data.name  = 'Voltage at point X'
data.unit  = 'mV'

You see, this offers many elegant ways to keep the data and the meaning packed together. And the name is not restricted to allowed names of variables.

Related Solutions

MATLAB: How to get the name of a MATLAB variable as a string

There is no direct way to get the name of a variable as a string, but there is a function called "inputname" that will return the name of a variable that was input into a function:

https://www.mathworks.com/help/matlab/ref/inputname.html

Using this, you can create a short function that, given a variable, will output the name of it as a string, as in the following example:

function out = getVarName(var)
    out = inputname(1);
end

As long as the file is included on the MATLAB path, you can use the function in the following way:

>> x = 1:10; % example data
>> plot(x)
>> title(getVarName(x))

MATLAB: How to pass a variable to a function with the variable name and data visible to the function without passing both a string and a data variable separately in MATLAB 7.0 (R14)

You can accomplish this by using the EVALIN function. As an example, if you want to write a function to plot a workspace variable and set the plot title to the name of the variable, you could use the following function:

function plotname(name)
% where name is passed as a string
data = evalin('base',name);
plot(data)
title(name)

an example of using this code from the MATLAB command prompt is below:

myData = 1:10;
plotname myData  %can also use plotname('myData')

This will plot the data contained in "myData" and set the title of the plot to be "myData".

Best Answer

Related Solutions

MATLAB: How to get the name of a MATLAB variable as a string

MATLAB: How to pass a variable to a function with the variable name and data visible to the function without passing both a string and a data variable separately in MATLAB 7.0 (R14)

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