Error using cross validation with plsregress

Hi everyone,

I am running a PLS regression and try to perform cross validation (k-fold) with matlab data.

load spectra
X = NIR;
y = octane;
[XL,yl,XS,YS,beta,PCTVAR,MSE] = plsregress(X,y,10,'CV',10);

Unfortunately, this error appear:

Could you explain to me how to solve it please?

Thank you in advance for your help.

Bruno

[Adam Danz]

When I run the example code you shared, it runs smoothly in r2020b.

What release are you using?

You may have a file or function named "crossval" that is shadowing Matlab's crossval() function.

The line in the screenshot that indicates the error in that function contains variable names and commands that are not in the built-in crossval() function, at least not in r2020b. But that could also be explained by using an older release of Matlab.

To list functions with the name crossval,

which crossval -all

[bruno ebel]

Thank you Adam for your kind answer. I've listed crossval function and and indeed, the main function of matlab is hidden by one of a toolbox:

>> which crossval -all
C:\Program Files\MATLAB\R2017a\toolbox\pls_toolbox_862\crossval.m
C:\Program Files\MATLAB\R2017a\toolbox\stats\stats\crossval.m      % Shadowed

How can I fix it?

Thanks again,

Bruno

[bruno ebel]

Ok, i've changed the order of the folder in the set up. Thanks again :-)

[bruno ebel]

But errors are still here...

Answer 1

[Adam Danz]

Based on the results of

which crossval -all

a function with the same name from a 3rd party toolbox (pls toolbox) is shadowing Matlab's crossval function which is called by plsregress.

If you are not using the pls toolbox, remove it from your Matlab path using

rmpath('C:\Program Files\MATLAB\R2017a\toolbox\pls_toolbox_862')
% or 
rmpath([matlabroot, '\toolbox\pls_toolbox_862'])

If you are using the pls toolbox, you can use Julian's answer explained here

https://www.mathworks.com/matlabcentral/answers/149059-how-do-i-invoke-a-shadowed-core-matlab-function-not-built-in-from-an-overloaded-function-of-same

It grabs the function handle from Matlab's crossval function and assigns it to a variable that you can use in addition to the crossval version in pls toolbox.

[bruno ebel]

And if i'm using it ?

[Adam Danz]

In the past when I faced the same problem I used Julian's answer explained here

https://www.mathworks.com/matlabcentral/answers/149059-how-do-i-invoke-a-shadowed-core-matlab-function-not-built-in-from-an-overloaded-function-of-same

I'll update my answer to include this.

[bruno ebel]

ok thank you!