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