Cross validation in matlab

LesterLim - 2022-04-23T10:45:11+00:00

Question: Cross validation in matlab

What are the steps to performing cross validation on labels of data to get the accuracy of the results?  

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Expert Answer

Neeta Dsouza answered . 2025-11-20

Cross-validation is a powerful technique for evaluating the accuracy of your model by partitioning the data into training and testing sets multiple times. Here are the steps to perform cross-validation on the labels of data in MATLAB:

1. Prepare Your Data: Organize your data into a matrix X (features) and a vector Y (labels).

2. Choose a Cross-Validation Method: The most common method is K-fold cross-validation, where the data is divided into K equally-sized folds.

3. Create a Cross-Validation Partition: Use the cvpartition function to create a partition for K-fold cross-validation.

   matlab

   K = 5; % Number of folds
   cv = cvpartition(Y, 'KFold', K);
   

4. Train and Evaluate the Model: For each fold, train the model on the training set and evaluate it on the validation set. Use a loop to iterate over each fold.

   matlab

   accuracy = zeros(K, 1);
   for i = 1:K
       trainIdx = training(cv, i);
       testIdx = test(cv, i);
   
       % Train the model
       model = fitcsvm(X(trainIdx, :), Y(trainIdx)); % Example using SVM
   
       % Test the model
       predictions = predict(model, X(testIdx, :));
       accuracy(i) = sum(predictions == Y(testIdx)) / length(predictions);
   end
   

5. Calculate Overall Accuracy: Compute the mean accuracy over all folds.

   matlab

   overallAccuracy = mean(accuracy);
   

6. Analyze and Interpret the Results: Use the overall accuracy to evaluate the performance of your model.

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