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% STK_SAMPLING_REGULARGRID builds a regular grid
%
% CALL: X = stk_sampling_regulargrid (N, DIM)
%
% builds a regular grid in the DIM-dimensional hypercube [0; 1]^DIM. If N is
% an integer, a grid of size N is built; in this case, acceptable sizes are
% such that N^(1/DIM) is an integer. If N is a vector of length N, a grid of
% size prod(N) is built, with N(j) points on coordinate j.
%
% CALL: X = stk_sampling_regulargrid (N, DIM, BOX)
%
% does the same thing in the DIM-dimensional hyperrectangle specified by the
% argument BOX, which is a 2 x DIM matrix where BOX(1, j) and BOX(2, j) are
% the lower- and upper-bound of the interval on the j^th coordinate.
%
% See also: linspace
% Copyright Notice
%
% Copyright (C) 2017 CentraleSupelec
% Copyright (C) 2011-2014 SUPELEC
%
% Authors: Julien Bect <julien.bect@centralesupelec.fr>
% Emmanuel Vazquez <emmanuel.vazquez@centralesupelec.fr>
% Copying Permission Statement
%
% This file is part of
%
% STK: a Small (Matlab/Octave) Toolbox for Kriging
% (http://sourceforge.net/projects/kriging)
%
% STK 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.
%
% STK 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 STK. If not, see <http://www.gnu.org/licenses/>.
function x = stk_sampling_regulargrid (n, dim, box)
if nargin > 3,
stk_error ('Too many input arguments.', 'TooManyInputArgs');
end
% Read argument dim
if (nargin < 2) || ((nargin < 3) && (isempty (dim)))
dim = 1; % Default dimension
elseif (nargin > 2) && (~ isempty (box))
dim = size (box, 2);
end
% Read argument 'box'
if (nargin < 3) || isempty (box)
xmin = zeros (1, dim);
xmax = ones (1, dim);
box_colnames = {};
else
box = stk_hrect (box); % convert input argument to a proper box
box_data = double (box);
box_colnames = get (box, 'colnames');
xmin = box_data(1, :);
xmax = box_data(2, :);
end
if length (n) == 1
n_coord = round (n^(1/dim));
if n_coord ^ dim ~= n,
stk_error ('n^(1/dim) should be an integer', 'InvalidArgument');
end
n = n_coord * ones (1, dim);
else
if length (n) ~= dim
errmsg = 'n should either be a scalar or a vector of length d';
stk_error (errmsg, 'IncorrectSize');
end
end
% levels
levels = cell (1, dim);
for j = 1:dim,
levels{j} = linspace (xmin(j), xmax(j), n(j));
end
x = stk_factorialdesign (levels, box_colnames);
end % function
%#ok<*TRYNC>
%%
% Check error for incorrect number of input arguments
%!shared x, n, dim, box
%! n = 9; dim = 2; box = [0, 0; 1, 1];
%!error x = stk_sampling_regulargrid ();
%!test x = stk_sampling_regulargrid (n);
%!test x = stk_sampling_regulargrid (n, dim);
%!test x = stk_sampling_regulargrid (n, dim, box);
%!error x = stk_sampling_regulargrid (n, dim, box, pi);
%%
% Check that the output is an stk_dataframe
% (all stk_sampling_* functions should behave similarly in this respect)
% and an stk_factorialdesign (special kind of stk_dataframe)
%!assert (isa (x, 'stk_dataframe'));
%!assert (isa (x, 'stk_factorialdesign'));
%%
% Check that column names are properly set, if available in box
%!assert (isequal (x.colnames, {}));
%!test
%! cn = {'W', 'H'}; box = stk_hrect (box, cn);
%! x = stk_sampling_regulargrid (n, dim, box);
%! assert (isequal (x.colnames, cn));
%%
% Check output argument
%!test
%! for dim = 1:3,
%! n = 3^dim;
%! x = stk_sampling_regulargrid(n, dim);
%! assert(isequal(size(x), [n dim]));
%! u = double(x); u = u(:);
%! assert(~any(isnan(u) | isinf(u)));
%! assert((min(u) >= 0) && (max(u) <= 1));
%! end
%!test
%! nn = [3 4 5];
%! for dim = 1:3,
%! x = stk_sampling_regulargrid(nn(1:dim), dim);
%! assert(isequal(size(x), [prod(nn(1:dim)) dim]));
%! u = double(x); u = u(:);
%! assert(~any(isnan(u) | isinf(u)));
%! assert((min(u) >= 0) && (max(u) <= 1));
%! end
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