wolffd@0: function [me, st, md, no] = nanstats(D)
wolffd@0: 
wolffd@0: %NANSTATS Statistical operations that ignore NaNs and Infs.
wolffd@0: %
wolffd@0: % [mean, std, median, nans] = nanstats(D)
wolffd@0: %
wolffd@0: %  Input and output arguments: 
wolffd@0: %   D   (struct) data or map struct
wolffd@0: %       (matrix) size dlen x dim
wolffd@0: %
wolffd@0: %   me  (double) columnwise mean
wolffd@0: %   st  (double) columnwise standard deviation
wolffd@0: %   md  (double) columnwise median
wolffd@0: %   no  (vector) columnwise number of samples (finite, not-NaN)
wolffd@0: 
wolffd@0: % Contributed to SOM Toolbox vs2, February 2nd, 2000 by Juha Vesanto
wolffd@0: % http://www.cis.hut.fi/projects/somtoolbox/
wolffd@0: 
wolffd@0: % Version 2.0beta juuso 300798 200900
wolffd@0: 
wolffd@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
wolffd@0: %% check arguments
wolffd@0: 
wolffd@0: (nargchk(1, 1, nargin));  % check no. of input args is correct
wolffd@0: 
wolffd@0: if isstruct(D), 
wolffd@0:   if strcmp(D.type,'som_map'), D = D.codebook;
wolffd@0:   else D = D.data;
wolffd@0:   end
wolffd@0: end
wolffd@0: [dlen dim] = size(D);
wolffd@0: me = zeros(dim,1)+NaN;
wolffd@0: md = me;
wolffd@0: st = me;
wolffd@0: no = me;
wolffd@0: 
wolffd@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
wolffd@0: %% computation
wolffd@0: 
wolffd@0: for i = 1:dim,
wolffd@0:   ind = find(isfinite(D(:, i))); % indices of non-NaN/Inf elements
wolffd@0:   n   = length(ind);             % no of non-NaN/Inf elements
wolffd@0: 
wolffd@0:   me(i) = sum(D(ind, i)); % compute average
wolffd@0:   if n == 0, me(i) = NaN; else me(i) = me(i) / n; end
wolffd@0: 
wolffd@0:   if nargout>1, 
wolffd@0:     md(i) = median(D(ind, i)); % compute median
wolffd@0: 
wolffd@0:     if nargout>2, 
wolffd@0:       st(i) = sum((me(i) - D(ind, i)).^2); % compute standard deviation
wolffd@0:       if n == 0,     st(i) = NaN;
wolffd@0:       elseif n == 1, st(i) = 0;
wolffd@0:       else st(i) = sqrt(st(i) / (n - 1));
wolffd@0:       end
wolffd@0: 
wolffd@0:       if nargout>3, 
wolffd@0: 	no(i) = n; % number of samples (finite, not-NaN)
wolffd@0:       end
wolffd@0:     end
wolffd@0:   end
wolffd@0: end
wolffd@0: 
wolffd@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
wolffd@0: