Mercurial > hg > octave-nkf
annotate scripts/geometry/griddatan.m @ 8203:a9da991c77aa
update contrib.txi
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Wed, 08 Oct 2008 14:29:51 -0400 |
| parents | ec0a13863eb7 |
| children | eb63fbe60fab |
| rev | line source |
|---|---|
| 7017 | 1 ## Copyright (C) 2007 David Bateman |
| 6823 | 2 ## |
| 3 ## This file is part of Octave. | |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7016 | 7 ## the Free Software Foundation; either version 3 of the License, or (at |
| 8 ## your option) any later version. | |
| 6823 | 9 ## |
| 10 ## Octave is distributed in the hope that it will be useful, but | |
| 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 ## General Public License for more details. | |
| 14 ## | |
| 15 ## You should have received a copy of the GNU General Public License | |
| 7016 | 16 ## along with Octave; see the file COPYING. If not, see |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 6823 | 18 |
| 19 ## -*- texinfo -*- | |
| 20 ## @deftypefn {Function File} {@var{yi} =} griddatan (@var{x}, @var{y}, @var{xi}, @var{method}, @var{options}) | |
| 21 ## | |
| 22 ## Generate a regular mesh from irregular data using interpolation. | |
| 23 ## The function is defined by @code{@var{y} = f (@var{x})}. | |
| 24 ## The interpolation points are all @var{xi}. | |
| 25 ## | |
| 6826 | 26 ## The interpolation method can be @code{"nearest"} or @code{"linear"}. |
| 27 ## If method is omitted it defaults to @code{"linear"}. | |
| 6823 | 28 ## @seealso{griddata, delaunayn} |
| 29 ## @end deftypefn | |
| 30 | |
| 7017 | 31 ## Author: David Bateman <dbateman@free.fr> |
| 32 | |
| 6826 | 33 function yi = griddatan (x, y, xi, method, varargin) |
| 34 | |
| 6823 | 35 if (nargin == 3) |
| 6826 | 36 method = "linear"; |
| 6823 | 37 endif |
| 38 if (nargin < 3) | |
| 6826 | 39 print_usage (); |
| 6823 | 40 endif |
| 41 | |
| 6826 | 42 if (ischar (method)) |
| 43 method = tolower (method); | |
| 6823 | 44 endif |
| 45 | |
| 6826 | 46 [m, n] = size (x); |
| 47 [mi, ni] = size (xi); | |
| 6823 | 48 |
| 6826 | 49 if (n != ni || size (y, 1) != m || size (y, 2) != 1) |
| 6823 | 50 error ("griddatan: dimensional mismatch"); |
| 51 endif | |
| 52 | |
| 53 ## triangulate data | |
| 54 ## tri = delaunayn(x, varargin{:}); | |
| 6826 | 55 tri = delaunayn (x); |
| 6823 | 56 |
| 6826 | 57 yi = nan (mi, 1); |
| 6823 | 58 |
| 6826 | 59 if (strcmp (method, "nearest")) |
| 6823 | 60 ## search index of nearest point |
| 6826 | 61 idx = dsearchn (x, tri, xi); |
| 62 valid = !isnan (idx); | |
| 6823 | 63 yi(valid) = y(idx(valid)); |
| 64 | |
| 6826 | 65 elseif (strcmp (method, "linear")) |
| 6823 | 66 ## search for every point the enclosing triangle |
| 6826 | 67 [tri_list, bary_list] = tsearchn (x, tri, xi); |
| 6823 | 68 |
| 69 ## only keep the points within triangles. | |
| 6826 | 70 valid = !isnan (tri_list); |
| 71 tri_list = tri_list(!isnan (tri_list)); | |
| 72 bary_list = bary_list(!isnan (tri_list), :); | |
| 73 nr_t = rows (tri_list); | |
| 6823 | 74 |
| 75 ## assign x,y for each point of simplex | |
| 6826 | 76 xt = reshape (x(tri(tri_list,:),:), [nr_t, n+1, n]); |
| 6823 | 77 yt = y(tri(tri_list,:)); |
| 78 | |
| 79 ## Use barycentric coordinate of point to calculate yi | |
| 80 yi(valid) = sum (y(tri(tri_list,:)) .* bary_list, 2); | |
| 81 | |
| 82 else | |
| 6826 | 83 error ("griddatan: unknown interpolation method"); |
| 6823 | 84 endif |
| 85 | |
| 86 endfunction | |
| 87 | |
|
8153
ec0a13863eb7
Only run tests that depend on HDF5 and QHull if Octave was actually
Soren Hauberg <hauberg@gmail.com>
parents:
7017
diff
changeset
|
88 %!testif HAVE_QHULL |
| 6823 | 89 %! [xx,yy] = meshgrid(linspace(-1,1,32)); |
| 90 %! xi = [xx(:), yy(:)]; | |
| 91 %! x = (2 * rand(100,2) - 1); | |
| 92 %! x = [x;1,1;1,-1;-1,-1;-1,1]; | |
| 93 %! y = sin(2*(sum(x.^2,2))); | |
| 94 %! zz = griddatan(x,y,xi,'linear'); | |
| 95 %! zz2 = griddata(x(:,1),x(:,2),y,xi(:,1),xi(:,2),'linear'); | |
| 96 %! assert (zz, zz2, 1e-10) | |
| 97 | |
|
8153
ec0a13863eb7
Only run tests that depend on HDF5 and QHull if Octave was actually
Soren Hauberg <hauberg@gmail.com>
parents:
7017
diff
changeset
|
98 %!testif HAVE_QHULL |
| 6823 | 99 %! [xx,yy] = meshgrid(linspace(-1,1,32)); |
| 100 %! xi = [xx(:), yy(:)]; | |
| 101 %! x = (2 * rand(100,2) - 1); | |
| 102 %! x = [x;1,1;1,-1;-1,-1;-1,1]; | |
| 103 %! y = sin(2*(sum(x.^2,2))); | |
| 104 %! zz = griddatan(x,y,xi,'nearest'); | |
| 105 %! zz2 = griddata(x(:,1),x(:,2),y,xi(:,1),xi(:,2),'nearest'); | |
| 106 %! assert (zz, zz2, 1e-10) |