MatLab: Index Exceed Matrix Dimension - matlab

Question

I have following 10 fold implementation, I am using data set publish by UCI Machine learning, Here is the link for the data set:
Here are my dimensions
x =
data: [178x13 double]
labels: [178x1 double]
This is the error that I am getting
Index exceeds matrix dimensions.
Error in GetTenFold (line 33)
results_cell{i,2} = shuffledMatrix(testRows ,:);
This is my code:
%Function that accept data file as a name and the number of folds
%For the cross fold
function [results_cell] = GetTenFold(dataFile, x)
%loading the data file
dataMatrix = load(dataFile);
%combine the data and labels as one matrix
X = [dataMatrix.data dataMatrix.labels];
%geting the length of the of matrix
dataRowNumber = length(dataMatrix.data);
%shuffle the matrix while keeping rows intact
shuffledMatrix = X(randperm(size(X,1)),:);
crossValidationFolds = x;
%Assinging number of rows per fold
numberOfRowsPerFold = dataRowNumber / crossValidationFolds;
crossValidationTrainData = [];
crossValidationTestData = [];
%Assigning 10X2 cell to hold each fold as training and test data
results_cell = cell(10,2);
%starting from the first row and segment it based on folds
i = 1;
for startOfRow = 1:numberOfRowsPerFold:dataRowNumber
testRows = startOfRow:startOfRow+numberOfRowsPerFold-1;
if (startOfRow == 1)
trainRows = (max(testRows)+1:dataRowNumber);
else
trainRows = [1:startOfRow-1 max(testRows)+1:dataRowNumber];
i = i + 1;
end
%for i=1:10
results_cell{i,1} = shuffledMatrix(trainRows ,:);
results_cell{i,2} = shuffledMatrix(testRows ,:); %This is where I am getting my dimension error
%end
%crossValidationTrainData = [crossValidationTrainData ; shuffledMatrix(trainRows ,:)];
%crossValidationTestData = [crossValidationTestData ;shuffledMatrix(testRows ,:)];
end
end

Answer 1

You're looping over 1:numberOfRowsPerFold:dataRowNumber which is 1:x:178 and i increments every time. So that's a way you can get the index out of bounds error on results_cell.
Another way to get the error is that testRows selects rows out of bound of shuffledMatrix.
Learn to debug
To pause the code and start debugging when the error occurs, run dbstop if error before executing your code. This way the compiler goes in debug mode upon encountering an error and you can inspect the state of variables right before things mess up.
(to disable this debugging mode, run dbclear if error.)