changelog shortlog tags changeset files revisions annotate raw

scripts/statistics/base/iqr.m

changeset 10289: 4b124317dc38
parent:eb63fbe60fab
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (44 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1995, 1996, 1997, 1998, 2000, 2002, 2003, 2004, 2005,

     2##               2006, 2007, 2009 Kurt Hornik

     3##

     4## This file is part of Octave.

     5##

     6## Octave is free software; you can redistribute it and/or modify it

     7## under the terms of the GNU General Public License as published by

     8## the Free Software Foundation; either version 3 of the License, or (at

     9## your option) any later version.

    10##

    11## Octave is distributed in the hope that it will be useful, but

    12## WITHOUT ANY WARRANTY; without even the implied warranty of

    13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14## General Public License for more details.

    15##

    16## You should have received a copy of the GNU General Public License

    17## along with Octave; see the file COPYING.  If not, see

    18## <http://www.gnu.org/licenses/>.

    19

    20## -*- texinfo -*-

    21## @deftypefn {Function File} {} iqr (@var{x}, @var{dim})

    22## If @var{x} is a vector, return the interquartile range, i.e., the

    23## difference between the upper and lower quartile, of the input data.

    24##

    25## If @var{x} is a matrix, do the above for first non-singleton

    26## dimension of @var{x}.  If the option @var{dim} argument is given,

    27## then operate along this dimension.

    28## @end deftypefn

    29

    30## Author KH <Kurt.Hornik@wu-wien.ac.at>

    31## Description: Interquartile range

    32

    33function y = iqr (x, dim)

    34

    35  if (nargin != 1 && nargin != 2)

    36    print_usage ();

    37  endif

    38

    39  nd = ndims (x);

    40  sz = size (x);

    41  nel = numel (x);

    42  if (nargin != 2)

    43    ## Find the first non-singleton dimension.

    44    dim  = 1;

    45    while (dim < nd + 1 && sz(dim) == 1)

    46      dim = dim + 1;

    47    endwhile

    48    if (dim > nd)

    49      dim = 1;

    50    endif

    51  else

    52    if (! (isscalar (dim) && dim == round (dim))

    53	&& dim > 0

    54	&& dim < (nd + 1))

    55      error ("iqr: dim must be an integer and valid dimension");

    56    endif

    57  endif

    58

    59  ## This code is a bit heavy, but is needed until empirical_inv 

    60  ## takes other than vector arguments.

    61  c = sz(dim);

    62  sz(dim) = 1;

    63  y = zeros (sz);

    64  stride = prod (sz(1:dim-1));

    65  for i = 1 : nel / c;

    66    offset = i;

    67    offset2 = 0;

    68    while (offset > stride)

    69      offset -= stride;

    70      offset2++;

    71    endwhile

    72    offset += offset2 * stride * c;

    73    rng = [0 : c-1] * stride + offset;

    74

    75    y (i) = empirical_inv (3/4, x(rng)) - empirical_inv (1/4, x(rng));

    76  endfor

    77

    78endfunction