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author | John W. Eaton <jwe@octave.org> |
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date | Thu, 20 Jan 2011 17:35:29 -0500 |
parents | fd0a3ac60b0e |
children | 6b2f14af2360 |
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## Copyright (C) 1995-2011 Kurt Hornik ## ## This file is part of Octave. ## ## Octave 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 3 of the License, or (at ## your option) any later version. ## ## Octave 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 Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {} iqr (@var{x}) ## @deftypefnx {Function File} {} iqr (@var{x}, @var{dim}) ## Return the interquartile range, i.e., the difference between the upper ## and lower quartile of the input data. If @var{x} is a matrix, do the ## above for first non-singleton dimension of @var{x}. ## ## If the optional argument @var{dim} is given, operate along this dimension. ## ## As a measure of dispersion, the interquartile range is less affected by ## outliers than either @code{range} or @code{std}. ## @seealso{range, std} ## @end deftypefn ## Author KH <Kurt.Hornik@wu-wien.ac.at> ## Description: Interquartile range function y = iqr (x, dim) if (nargin != 1 && nargin != 2) print_usage (); endif if (!(ismatrix (x) && isnumeric (x)) || isscalar(x)) error ("iqr: X must be a numeric vector or matrix"); endif nd = ndims (x); sz = size (x); nel = numel (x); if (nargin != 2) ## Find the first non-singleton dimension. dim = find (sz > 1, 1); if (isempty (dim)) dim = 1; endif else if (!(isscalar (dim) && dim == fix (dim)) || !(1 <= dim && dim <= nd)) error ("iqr: DIM must be an integer and a valid dimension"); endif endif ## This code is a bit heavy, but is needed until empirical_inv ## takes other than vector arguments. c = sz(dim); sz(dim) = 1; y = zeros (sz); stride = prod (sz(1:dim-1)); for i = 1 : nel / c; offset = i; offset2 = 0; while (offset > stride) offset -= stride; offset2++; endwhile offset += offset2 * stride * c; rng = [0 : c-1] * stride + offset; y (i) = empirical_inv (3/4, x(rng)) - empirical_inv (1/4, x(rng)); endfor endfunction %!assert (iqr (1:101), 50); %%!test %%! x = [1:100]; %%! n = iqr (x, 0:10); %%! assert (n, [repmat(100, 1, 10), 1]); %!error iqr (); %!error iqr (1, 2, 3); %!error iqr (1); %!error iqr ([true, true]); %!error iqr (1:10, 3);