Mercurial > hg > octave-lojdl
changeset 7551:5ed0cb9e9584
rectint.m: added
author | bill@denney.ws |
---|---|
date | Tue, 04 Mar 2008 15:07:44 -0500 |
parents | bffb1e2ab732 |
children | 6070c3bd69c4 |
files | scripts/ChangeLog scripts/geometry/rectint.m |
diffstat | 2 files changed, 95 insertions(+), 0 deletions(-) [+] |
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--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,7 @@ +2008-03-04 Bill Denney <bill@denney.ws> + + * geometry/rectint.m: New function. + 2008-03-04 Michael Goffioul <michael.goffioul@gmail.com> * pkg/pkg.m (pkg:configure_make): Make it work with recent changes in
new file mode 100644 --- /dev/null +++ b/scripts/geometry/rectint.m @@ -0,0 +1,91 @@ +## Copyright (C) 2008 Bill Denney +## +## 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} {@var{area} =} rectint (@var{a}, @var{b}) +## +## Compute the area of intersection of rectangles in @var{a} and +## rectangles in @var{b}. Rectangles are defined as [x y width height] +## where x and y are the minimum values of the two orthogonal +## dimensions. +## +## If @var{a} or @var{b} are matrices, then the output, @var{area}, is a +## matrix where the ith row corresponds to the ith row of a and the jth +## column corresponds to the jth row of b. +## +## @seealso{polyarea} +## @end deftypefn + +## Author: Bill Denney <bill@denney.ws> + +function area = rectint (a, b) + + if (nargin != 2) + print_usage (); + elseif (ndims (a) != 2 || ndims (b) != 2) + error ("rectint: expecting arguments to be 2-d arrays"); + elseif (columns (a) != 4) + error ("rectint: a must have 4 columns"); + elseif (columns (b) != 4) + error ("rectint: b must have 4 columns"); + endif + + area = zeros (rows (a), rows (b)); + for i = 1:rows (area) + r1 = a(i,:); + for j = 1:columns (area) + r2 = b(j,:); + area(i,j) = (overlap (r1([1, 3]), r2([1, 3])) + * overlap (r1([2, 4]), r2([2, 4]))); + endfor + endfor + +endfunction + +function amt = overlap (r1, r2) + + ## Determine whether two ranges overlap. Ranges are given as [value + ## offset] + amt = 0; + + ## Make sure that the values are in order. + r1 = sort ([r1(1), r1(1)+r1(2)]); + r2 = sort ([r2(1), r2(1)+r2(2)]); + + ## Is the first point in range 1 in the middle of range 2? + p1 = sum (r1(1) <= r2) == 1; + ## is the second? + p2 = sum (r1(2) <= r2) == 1; + if (p1) + if (p2) + amt = r1(2) - r1(1); + else + amt = r2(2) - r1(1); + endif + elseif (sum (r1(2) < r2) == 1) + amt = r1(2) - r2(1); + endif + +endfunction + +## Tests +%!assert(rectint([0 0 1 1], [1 1 2 2]), 0) +%!assert(rectint([0 0 1 1], [0.5 0.5 2 2]), 0.25) +%!assert(rectint([0 0 1 1;0.5 0.5 1 1], [1 1 2 2]), [0;0.25]) +%!assert(rectint([1 1 2 2], [0 0 1 1;0.5 0.5 1 1]), [0 0.25]) +