Error using Classificationlearner model in Simulink

I used Classification learner App with a Fine KNN model that I called 'model_test'.

Now I want to use it in simulink.

So, I used a function block with the inputs of my model and 'model_test' as a parameter :

function y = predic(Fflown,N1n1,N2n1,N3n1,Taun1, model_test)

coder.extrinsic('model_test');

coder.extrinsic('model_test.predictFcn');

T=[Fflown,N1n1,N2n1,N3n1,Taun1];

y=0;

y = model_test.predictFcn(T);

end

But I run the simulink model, I have the error :

'MATLAB class 'function_handle' found at 'model_test.predictFcn' is unsupported.

Parameter 'model_test''

I saw that I may should use save CompactModel to export my Classification learner but when I try it I have another error :

"Undefined function 'toStruct' for input arguments of type 'ClassificationKNN'.

Error in saveCompactModel (line 17)

classificationStruct = toStruct(classificationObj); %#ok<NASGU>""

Answer 1

[Sean de Wolski]

Unfortunately this workflow is more painful than it should be. I've found the best set of steps is to:

• Generate the code for the model in classification learner.
• Copy out the relevant parts that call the classification training algorithm into a script, in this case fitcknn, and then retrain the model from the script.
• The output will now be a ClassificationKNN model that you can call saveCompactModel on.
• Then from the Simulink function:

function c = useModel(x)
persistent model
if isempty(model)
    model = loadCompactModel('savedCompactKNN.mat');
end
c = predict(model, x)
end

You'll notice that I don't need coder.extrinsic as this will generate code.

If you did want to reuse the already trained model, you'll need to grab that property of the trainedClassifier struct and save it:

saveCompactModel(trainedClassifier.ClassificationKNN) % or similar

But then you'll need to map all of the inputs to it which may not be as straight forward as just retraining it with the fitcknn fucntion directly.

Feel free to private message me if you'd like me to walk you through this. I'm trying to find users to convince dev this should be easier.

[Yougzz]

Thank you for your answer.

I tried it but it still doesn't work.

I obtain a ClassificationKNN model from my generated code but when I call saveCompactModel on, I have the error :

"Undefined function 'toStruct' for input arguments of type 'ClassificationKNN'.

Error in saveCompactModel (line 17)

classificationStruct = toStruct(classificationObj); %#ok<NASGU>"

The function "toStruct" in saveCompactModel doesn't work with.

[Yougzz]

my classificationKNN model :

"classKNN =

ClassificationKNN

PredictorNames: {'Fflown' 'N1n1' 'N2n1' 'N3n1' 'Taun1'}

ResponseName: 'Y'

CategoricalPredictors: []

ClassNames: [1×160 double]

ScoreTransform: 'none'

NumObservations: 57252

Distance: 'euclidean'

NumNeighbors: 1

Properties, Methods "

My call to saveCompactModel : "saveCompactModel(classKNN,'savedCompactKNN')"

the error : "Undefined function 'toStruct' for input arguments of type 'ClassificationKNN'.

Error in saveCompactModel (line 17)

classificationStruct = toStruct(classificationObj); %#ok<NASGU> "

I am using MATLAB R2016b, do your thiink that's a reason ? because I heard that only SVM, linear models and ECOCS models are supported for code generation but not the KNN models in R2016b.

[Sean de Wolski]

R2016b is very likely the reason, it's supported by 19a

[Yougzz]

Yes, I checked, It was the problem.

[Le Truong An]

I have the same problem. I am using 2017a.

Do you have any way to solve this problem?

Answer 2

[Tugce Anliak]

Hi i have same issue with a regressionlearner Model that i trained with the App --> saved Model or compact model and try to use MatlabFunction in Simulink and get Errors.

function y = fcn(x1,x2,x3,x4,x5)

y = trainedModel08072019.predictFcn(x1,x2,x3,x4,x5);

This is the Error I get from Matlab:

Undefined function or variable 'trainedModel08072019'.

Function 'MATLAB Function' (#128.38.58), line 3, column 5:

"trainedModel08072019"

Launch diagnostic report.

Component:MATLAB Function | Category:Coder error

Errors occurred during parsing of MATLAB function 'TrainedModel_test/MATLAB Function'

Component:MATLAB Function | Category:Coder error

Simulink cannot determine sizes and/or types of the outputs for block 'TrainedModel_test/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Component:MATLAB Function | Category:Coder error

Simulink cannot determine sizes and/or types of the outputs for block 'TrainedModel_test/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Component:Simulink | Category:Model error

Error occurred in 'TrainedModel_test/MATLAB Function'.

Component:Simulink | Category:Model error

How is the correct form to call a simulink function

[Sean de Wolski]

Please create your own question.