MATLAB: If I use the following function to obtain scatter matrices then how could I pass the input data to this function ,please help me if anybody know?

amit nambair

function [B W]=scattermat(data,Y)
%FUNCTION THAT CALCULATES SCATTER MATRIX:
%   B:BETWEEN  CLASS SCATTER MATRIX
%   W:WITHIN CLASS SCATTER MATRIX
%
      [~, l]=size(data);         %CALCULATE SIZE OF DATA
      clases=unique(Y);          %GET VECTOR OF CLASSES
      tot_clases=length(clases); %HOW MANY CLASSES
      B=zeros(l,l);              %INIT B AND W
      W=zeros(l,l);           
      overallmean=mean(data);    %MEAN OVER ALL DATA
      for i=1:tot_clases
          clasei = find(Y==clases(i)); %GET DATA FOR EACH CLASS
          xi=data(clasei,:);
          mci=mean(xi);                       %MEAN PER CLASS
          xi=xi-repmat(mci,length(clasei),1); %Xi-MeanXi
          W=W+xi'*xi;                         %CALCULATE W
          B=B+length(clasei)*(mci-overallmean)'*(mci-overallmean); %CALCULATE B
      end
  end

Best Answer

The first input needs to be a 2D array with one sample per row. The second input needs to be a numeric vector of class numbers, one entry for each row.
(The second input could also be a character vector, one character for each row, or a categorical array. It could also be a vector of string objects, one for each row. But it cannot be a cell array of strings.)
Related Question