Mercurial > hg > octave-terminal
changeset 10395:aeb5b1e47978
new function: accumdim
author | Jaroslav Hajek <highegg@gmail.com> |
---|---|
date | Fri, 05 Mar 2010 11:11:01 +0100 |
parents | bc475cd49147 |
children | a0b51ac0f88a |
files | scripts/ChangeLog scripts/general/accumdim.m scripts/general/module.mk |
diffstat | 3 files changed, 142 insertions(+), 0 deletions(-) [+] |
line wrap: on
line diff
--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,7 @@ +2010-03-05 Jaroslav Hajek <highegg@gmail.com> + + * general/accumdim.m: New function. + 2010-03-05 Jaroslav Hajek <highegg@gmail.com> * optimization/fzero.m: Avoid division by zero.
new file mode 100644 --- /dev/null +++ b/scripts/general/accumdim.m @@ -0,0 +1,137 @@ +## Copyright (C) 2010 VZLU Prague +## +## 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} {} accumdim (@var{subs}, @var{vals}, @var{dim}, @var{sz}, @var{func}, @var{fillval}) +## Create an array by accumulating the slices of an array into the +## positions defined by their subscripts along a specified dimension. +## The subscripts are defined by the index vector @var{subs}. +## The dimension is specified by @var{dim}. If not given, it defaults +## to the first non-singleton dimension. +## +## The extent of the result matrix in the working dimension will be determined +## by the subscripts themselves. +## However, if @var{n} is defined it determines this extent. +## +## The default action of @code{accumdim} is to sum the subarrays with the +## same subscripts. This behavior can be modified by defining the @var{func} +## function. This should be a function or function handle that accepts an +## array and a dimension, and reduces the array along this dimension. +## As a special exception, the built-in @code{min} and @code{max} functions +## can be used directly, and @code{accumdim} accounts for the middle empty +## argument that is used in their calling. +## +## The slices of the returned array that have no subscripts associated with +## them are set to zero. Defining @var{fillval} to some other value allows +## these values to be defined. +## +## An example of the use of @code{accumarray} is: +## +## @example +## @group +## accumarray ([1,1,1;2,1,2;2,3,2;2,1,2;2,3,2], 101:105) +## @result{} ans(:,:,1) = [101, 0, 0; 0, 0, 0] +## ans(:,:,2) = [0, 0, 0; 206, 0, 208] +## @end group +## @end example +## +## @seealso{accumarray} +## @end deftypefn + +function A = accumdim (subs, val, dim, n = 0, func = [], fillval = 0) + + if (nargin < 2 || nargin > 5) + print_usage (); + endif + + if (isempty (fillval)) + fillval = 0; + endif + + if (isempty (func)) + func = @sum; + endif + + if (! isvector (subs)) + error ("accumdim: subs must be a subscript vector"); + elseif (! isindex (subs)) # creates index cache + error ("accumdim: indices must be positive integers"); + else + m = max (subs); + if (n == 0) + n = m; + elseif (n < m) + error ("accumdim: index out of range") + endif + endif + + ## The general case. + sz = size (val); + + if (nargin < 3) + [~, dim] = max (sz != 1); # first non-singleton dim + elseif (! isindex (dim, ndims (val))) + error ("accumdim: dim must be a valid dimension"); + endif + sz(dim) = n; + + ns = length (subs); + ## Sort indices. + [subs, idx] = sort (subs(:)); + ## Identify runs. + jdx = find (subs(1:ns-1) != subs(2:ns)); + jdx = [jdx; ns]; + ## Collect common slices. + szc = num2cell (sz); + szc{dim} = diff ([0; jdx]); + subsc = {':'}(ones (1, length (sz))); + subsc{dim} = idx; + val = mat2cell (val(subsc{:}), szc{:}); + ## Apply reductions. Special case min, max. + if (func == @min || func == @max) + val = cellfun (func, val, {[]}, {dim}, "uniformoutput", false); + else + val = cellfun (func, val, {dim}, "uniformoutput", false); + endif + subs = subs(jdx); + + ## Concatenate reduced slices. + val = cat (dim, val{:}); + + ## Construct matrix of fillvals. + if (fillval == 0) + A = zeros (sz, class (val)); + else + A = repmat (fillval, sz); + endif + + ## Set the reduced values. + subsc{dim} = subs; + A(subsc{:}) = val; + +endfunction + +%%test accumdim vs. accumarray + +%!shared a +%! a = rand (5, 5, 5); + +%!assert (accumdim ([1;3;1;3;3], a)(:,2,3), accumarray ([1;3;1;3;3], a(:,2,3))) +%!assert (accumdim ([2;3;2;2;2], a, 2, 4)(4,:,2), accumarray ([2;3;2;2;2], a(4,:,2), [1,4])) +%!assert (accumdim ([2;3;2;1;2], a, 3, 3, @min)(1,5,:), accumarray ([2;3;2;1;2], a(1,5,:), [1,1,3], @min)) +%!assert (accumdim ([1;3;2;2;1], a, 2, 3, @median)(4,:,5), accumarray ([1;3;2;2;1], a(4,:,5), [1,3], @median))