Why do I get error for xlabel all of a sudden?

Index exceeds the number of array elements. Index must not

exceed 10.

Error in readData (line 57)

xlabel('x');

I have a data.m with 8 rows and 3000 columns.

My plots were "working" (slight problem with the legend not showing for second line but good enough) but now I am getting this on Line 57.

I attached my script but it looks like this around line 57

%plot xy for task3 and 5

figure; hold on

%plot(task3_x, task3_y, task5_x, task5_y);

t3 = plot(task3_x, task3_y);

t3_name = 'task 3';

t5 = plot(task5_x, task5_y);

t5_name = 'task 5';

title('task 3 and 5');

xlabel('x'); % line 57

ylabel('y');

legend([t3, t5], [t3_name, t5_name]);

[DGM]

The legend is just a matter of using the right array type:

legend([t3, t5], {t3_name, t5_name});

The issue with xlabel() is probably because something is shadowing it. Possibly a variable or another file called "xlabel". You can find what MATLAB thinks xlabel() is:

which xlabel -all

/MATLAB/toolbox/matlab/graph2d/xlabel.m

If the results of running which aren't pointing to that file, then you've found the problem. For instance:

xlabel = 'this is what i call my x-axis'; 
which xlabel -all

xlabel is a variable.
/MATLAB/toolbox/matlab/graph2d/xlabel.m  % Shadowed

[Nobutaka Kim]

I ran which xlabel - all in the command window and get the same output as you.

I am unsure what you mean, "then you've found the problem."

[DGM]

If your output for which() is the same as the first example:

/MATLAB/toolbox/matlab/graph2d/xlabel.m

and nothing else, then there shouldn't be a problem.

If you get something like the second example, then the extraneous entry is the problem itself.

To demonstrate:

xlabel = 'this is what i call my x-axis'; % xlabel isn't a function anymore
xlabel('x') % this isn't a function call; it's indexing into a vector

Index exceeds the number of array elements. Index must not exceed 29.

'xlabel' appears to be both a function and a variable. If this is unintentional, use 'clear xlabel' to remove the variable 'xlabel' from the workspace.

This is happening because 'xlabel' is now a variable. When you try to call the function by the same name, you're actually indexing into the variable called xlabel. To be specific, it converts the char vector 'x' into its ASCII numeric value (120) and tries to retrieve the 120th element of the vector.

The solution is to find the variable called 'xlabel' and name it something else.

[Voss]

"The solution is to find the variable called 'xlabel' and name it something else."

Yes, or put a clear (or clear xlabel) at the top of your script readData.m.

[DGM]

That's a good point. It's always a good idea to keep the workspace clear of old variables from prior or unrelated code.

Answer 1

[Image Analyst]

@Nobutaka Kim, The code does not throw that error for me. So like DGM says, it's likely you ran a different script that placed a variable called xlabel into the base workspace so when this script runs, it throws an error because it thinks xlabel is an array instead of the function to label an axis. To debug, put this line in there. Either early in your script, or just type it into the command window:

which -all xlabel

Tell me what you see in the command window.

Answer 2

[Nobutaka Kim]

Thanks all for the kind advice.

I restarted Matlab and the error went away so it must have been a variable in the workspace as mentioned.