/usr/share/octave/packages/3.2/statistics-1.0.10/nanmedian.m is in octave-statistics 1.0.10-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | ## Copyright (C) 2001 Paul Kienzle
##
## 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/>.
## -*- texinfo -*-
## @deftypefn {Function File} @var{v} = nanmedian (@var{x})
## @deftypefnx{Function File} @var{v} = nanmedian (@var{x}, @var{dim})
## Compute the median of data while ignoring NaN values.
##
## This function is identical to the @code{median} function except that NaN values
## are ignored. If all values are NaN, the median is returned as NaN.
##
## @seealso{median, nanmin, nanmax, nansum, nanmean}
## @end deftypefn
function v = nanmedian (X, varargin)
if nargin < 1 || nargin > 2
usage ("v = nanmedian(X [, dim])");
endif
if nargin < 2
dim = min(find(size(X)>1));
if isempty(dim), dim=1; endif;
else
dim = varargin{:};
endif
sz = size (X);
if (prod (sz) > 1)
## Find lengths of datasets after excluding NaNs; valid datasets
## are those that are not empty after you remove all the NaNs
n = sz(dim) - sum (isnan(X),varargin{:});
## When n is equal to zero, force it to one, so that median
## picks up a NaN value below
n (n==0) = 1;
## Sort the datasets, with the NaN going to the end of the data
X = sort (X, varargin{:});
## Determine the offset for each column in single index mode
colidx = reshape((0:(prod(sz) / sz(dim) - 1)), size(n));
colidx = floor(colidx / prod(sz(1:dim-1))) * prod(sz(1:dim)) + ...
mod(colidx,prod(sz(1:dim-1)));
stride = prod(sz(1:dim-1));
## Average the two central values of the sorted list to compute
## the median, but only do so for valid rows. If the dataset
## is odd length, the single central value will be used twice.
## E.g.,
## for n==5, ceil(2.5+0.5) is 3 and floor(2.5+0.5) is also 3
## for n==6, ceil(3.0+0.5) is 4 and floor(3.0+0.5) is 3
## correction made for stride of data "stride*ceil(2.5-0.5)+1"
v = (X(colidx + stride*ceil(n./2-0.5) + 1) + ...
X(colidx + stride*floor(n./2-0.5) + 1)) ./ 2;
else
error ("nanmedian: invalid matrix argument");
endif
endfunction
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