/usr/share/octave/packages/geometry-1.7.0/geom2d/centroid.m is in octave-geometry 1.7.0-1build1.
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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 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 | ## Copyright (C) 2004-2011 David Legland <david.legland@grignon.inra.fr>
## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## All rights reserved.
##
## Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are met:
##
## 1 Redistributions of source code must retain the above copyright notice,
## this list of conditions and the following disclaimer.
## 2 Redistributions in binary form must reproduce the above copyright
## notice, this list of conditions and the following disclaimer in the
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##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
## AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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## ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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## -*- texinfo -*-
## @deftypefn {Function File} {@var{c} = } centroid (@var{points})
## @deftypefnx {Function File} {@var{c} = } centroid (@var{px}, @var{py})
## @deftypefnx {Function File} {@var{c} = } centroid (@dots{}, @var{mass})
## Compute centroid (center of mass) of a set of points.
##
## Computes the ND-dimensional centroid of a set of points.
## @var{points} is an array with as many rows as the number of points, and as
## many columns as the number of dimensions.
## @var{px} and @var{py} are two column vectors containing coordinates of the
## 2-dimensional points.
## The result @var{c} is a row vector with ND columns.
##
## If @var{mass} is given, computes center of mass of @var{points}, weighted by coefficient @var{mass}.
## @var{points} is a Np-by-Nd array, @var{mass} is Np-by-1 array, and @var{px} and @var{py} are
## also both Np-by-1 arrays.
##
## Example:
##
## @example
## pts = [2 2;6 1;6 5;2 4];
## centroid(pts)
## ans =
## 4 3
##@end example
##
## @seealso{points2d, polygonCentroid}
## @end deftypefn
function center = centroid(varargin)
## extract input arguments
# use empty mass by default
mass = [];
if nargin==1
# give only array of points
pts = varargin{1};
elseif nargin==2
# either POINTS+MASS or PX+PY
var = varargin{1};
if size(var, 2)>1
# arguments are POINTS, and MASS
pts = var;
mass = varargin{2};
else
# arguments are PX and PY
pts = [var varargin{2}];
end
elseif nargin==3
# arguments are PX, PY, and MASS
pts = [varargin{1} varargin{2}];
mass = varargin{3};
end
## compute centroid
if isempty(mass)
# no weight
center = mean(pts);
else
# format mass to have sum equal to 1, and column format
mass = mass(:)/sum(mass(:));
# compute weighted centroid
center = sum(bsxfun(@times, pts, mass), 1);
# equivalent to:
# center = sum(pts .* mass(:, ones(1, size(pts, 2))));
end
endfunction
%!test
%! points = [0 0;10 0;10 10;0 10];
%! centro = centroid(points);
%! assert ([5 5], centro, 1e-6);
%!test
%! points = [0 0;10 0;10 10;0 10];
%! centro = centroid(points(:,1), points(:,2));
%! assert ([5 5], centro, 1e-6);
%!test
%! points = [0 0;30 0;30 30;0 30];
%! centro = centroid(points, [1;1;1;3]);
%! assert ([10 20], centro, 1e-6);
%!test
%! points = [0 0;30 0;30 30;0 30];
%! centro = centroid(points(:,1), points(:,2), [1;1;1;3]);
%! assert ([10 20], centro, 1e-6);
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