function [discreteDataset] = discretize(dataset)
% the details of this discretizer are as follows
% N bin, equal Freq (equal number of items in each bin)

N = 5; % number of bins
binSize = ceil(size(dataset,1)/N); % number of instances in each bin

% make a same size matrix for discrete values
discreteDataset = -1 * ones(size(dataset,1),size(dataset,2));

% process each column of the dataset one at a time
% except the last column, which is the effort value
binCounter = 1;
for i = 1:(size(dataset,2)-1)
   [C IND] = sort(dataset(:,i);   % get the indices of sorted instances in column
   binCounter
   for j = 1:size(dataset,1)
          dataset(j,i) = binCounter;        
   end
end

end