Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nan-2.5.5 / median.m

diff --git a/octave_packages/nan-2.5.5/median.m b/octave_packages/nan-2.5.5/median.m
new file mode 100644 (file)
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+++ b/octave_packages/nan-2.5.5/median.m
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+function [y]=median(x,DIM)
+% MEDIAN data elements, 
+% [y]=median(x [,DIM])
+%
+% DIM  dimension
+%      1: median of columns
+%      2: median of rows
+%      N: median of  N-th dimension 
+%      default or []: first DIMENSION, with more than 1 element
+%
+% features:
+% - can deal with NaN's (missing values)
+% - accepts dimension argument like in Matlab in Octave, too. 
+% - compatible to Matlab and Octave 
+%
+% see also: SUMSKIPNAN
+ 
+%    This program is free software; you can redistribute it and/or modify
+%    it under the terms of the GNU General Public License as published by
+%    the Free Software Foundation; either version 2 of the License, or
+%    (at your option) any later version.
+%
+%    This program is distributed in the hope that it will be useful,
+%    but WITHOUT ANY WARRANTY; without even the implied warranty of
+%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+%    GNU General Public License for more details.
+%
+%    You should have received a copy of the GNU General Public License
+%    along with this program; If not, see <http://www.gnu.org/licenses/>.
+
+%      $Id: median.m 9033 2011-11-08 20:58:07Z schloegl $
+%      Copyright (C) 2000-2003,2009 by Alois Schloegl <alois.schloegl@gmail.com>       
+%       This function is part of the NaN-toolbox
+%       http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+global FLAG_NANS_OCCURED;
+
+% check dimension of x
+sz=size(x);
+
+% find the dimension for median
+if nargin<2,
+        DIM=min(find(sz>1));
+        if isempty(DIM), DIM=1; end;
+end;
+
+if DIM>length(sz),
+        sz = [sz,ones(1,DIM-length(sz))];
+end;
+
+D1 = prod(sz(1:DIM-1));
+D2 = sz(DIM);
+D3 = prod(sz(DIM+1:length(sz)));
+D0 = [sz(1:DIM-1),1,sz(DIM+1:length(sz))];
+y  = repmat(nan,D0);
+flag_MexKthElement = exist('kth_element','file')==3;
+
+for k = 0:D1-1,
+for l = 0:D3-1,
+        xi = k + l * D1*sz(DIM) + 1 ;
+        xo = k + l * D1 + 1;
+        t = x(xi+(0:sz(DIM)-1)*D1);
+        t = t(~isnan(t));
+        n = length(t);
+
+        if n==0,
+                y(xo) = nan;
+        elseif flag_MexKthElement, 
+               if (D1==1) t = t+0.0; end;      % make sure a real copy (not just a reference to x) is used
+               flag_KthE = 0; % fast kth_element can be used, because t does not contain any NaN and there is need to care about in-place sorting
+                if ~rem(n,2),
+                        y(xo) = sum( kth_element( double(t), n/2 + [0,1], flag_KthE) ) / 2;
+                elseif rem(n,2),
+                        y(xo) = kth_element(double(t), (n+1)/2, flag_KthE);
+                end;
+        else
+                t = sort(t);
+                if ~rem(n,2),
+                        y(xo) = (t(n/2) + t(n/2+1)) / 2;
+                elseif rem(n,2),
+                        y(xo) = t((n+1)/2);
+                end;
+        end
+
+        if (n<D2) 
+               FLAG_NANS_OCCURED = 1; 
+        end; 
+end;
+end;
+
+
+%!assert(median([1,NaN,3,inf,-inf]),2)
+%!assert(median([1,NaN,3,inf,4,-inf]),3)
+