Matlab error when evaluating a neural network

Hellow I am having an error when I am trying to evaluate a neural network. The code is as follows:

% Load the sample data
load fisheriris

% Extract the first two features as the predictors and the third feature as the response
X = meas(:,1:2);
y = meas(:,3);

% Split the data into training and test sets
rng(1); % For reproducibility
cv = cvpartition(y,'Holdout',0.3);
XTrain = X(training(cv),:);
YTrain = y(training(cv));
XTest = X(test(cv),:);
YTest = y(test(cv));

% Create a decision tree using entropy as the splitting criterion
tree = fitctree(XTrain,YTrain,'SplitCriterion','gdi');

% Evaluate the decision tree on the test set
YPred = predict(tree,XTest); 

treeAccuracy = mean(YPred == YTest);
fprintf('Decision tree accuracy: %.2f%%\n',treeAccuracy*100)

% Create a feedforward neural network
net = patternnet(10);

% Train the neural network
net = train(net,XTrain',YTrain');

% Evaluate the neural network on the test set
YPred = net(XTest')';
YPred = tree.ClassNames(YPred);
nnAccuracy = mean(YPred == YTest);
fprintf('Neural network accuracy: %.2f%%\n',nnAccuracy*100)

Error:

Array indices must be positive integers or logical values.

Error in classreg.learning.internal.DisallowVectorOps/subsref (line 22)

[varargout{1:nargout}] = builtin('subsref',this,s);

Error in TreeVSAnn (line 33)

YPred = tree.ClassNames(YPred);

Any help to fix this would be greatly appreciated.

[Vinayak]

Hi Killian,

I am able to execute this code snippet error-free.

Could you please re-check and confirm.

Thanks.

Answer 1

[KSSV]

These lines:

YPred = net(XTest')';
YPred = tree.ClassNames(YPred);
nnAccuracy = mean(YPred == YTest);
fprintf('Neural network accuracy: %.2f%%\n',nnAccuracy*100)

Should be:

YPred = net(XTest')';
nnAccuracy = mean(YPred == YTest);
fprintf('Neural network accuracy: %.2f%%\n',nnAccuracy*100)

You need not to index tree.ClassNames. You got your prediction already from the line:

YPred = net(XTest')';

But this is not the way to caclulate Accuracy.