Mercurial > hg > octave-nkf
annotate scripts/plot/contourc.m @ 10845:c0ffe159ba1a
version is now 3.3.52+
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Sun, 01 Aug 2010 14:50:51 -0400 |
| parents | 693e22af08ae |
| children | a4f482e66b65 |
| rev | line source |
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| 8920 | 1 ## Copyright (C) 2003, 2007, 2008, 2009 Shai Ayal |
| 6257 | 2 ## |
| 6440 | 3 ## This file is part of Octave. |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6257 | 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. | |
| 6257 | 9 ## |
| 6440 | 10 ## Octave is distributed in the hope that it will be useful, but |
| 6257 | 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/>. | |
| 6257 | 18 |
| 19 ## -*- texinfo -*- | |
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20 ## @deftypefn {Function File} {[@var{c}, @var{lev}] =} contourc (@var{x}, @var{y}, @var{z}, @var{vn}) |
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21 ## Compute isolines (contour lines) of the matrix @var{z}. |
| 6257 | 22 ## Parameters @var{x}, @var{y} and @var{vn} are optional. |
| 23 ## | |
| 24 ## The return value @var{lev} is a vector of the contour levels. | |
| 25 ## The return value @var{c} is a 2 by @var{n} matrix containing the | |
| 26 ## contour lines in the following format | |
| 27 ## | |
| 28 ## @example | |
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29 ## @group |
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30 ## @var{c} = [lev1, x1, x2, @dots{}, levn, x1, x2, ... |
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31 ## len1, y1, y2, @dots{}, lenn, y1, y2, @dots{}] |
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32 ## @end group |
| 6257 | 33 ## @end example |
| 34 ## | |
| 35 ## @noindent | |
| 36 ## in which contour line @var{n} has a level (height) of @var{levn} and | |
| 37 ## length of @var{lenn}. | |
| 38 ## | |
| 39 ## If @var{x} and @var{y} are omitted they are taken as the row/column | |
| 40 ## index of @var{z}. @var{vn} is either a scalar denoting the number of lines | |
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41 ## to compute or a vector containing the values of the lines. If only one |
| 6257 | 42 ## value is wanted, set @code{@var{vn} = [val, val]}; |
| 43 ## If @var{vn} is omitted it defaults to 10. | |
| 44 ## | |
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45 ## For example: |
| 6257 | 46 ## @example |
| 6592 | 47 ## @group |
| 48 ## x = 0:2; | |
| 49 ## y = x; | |
| 50 ## z = x' * y; | |
| 51 ## contourc (x, y, z, 2:3) | |
| 52 ## @result{} 2.0000 2.0000 1.0000 3.0000 1.5000 2.0000 | |
| 53 ## 2.0000 1.0000 2.0000 2.0000 2.0000 1.5000 | |
| 54 ## | |
| 55 ## @end group | |
| 6257 | 56 ## @end example |
| 57 ## @seealso{contour} | |
| 58 ## @end deftypefn | |
| 59 | |
| 7327 | 60 ## Author: Shai Ayal <shaiay@users.sourceforge.net> |
| 6257 | 61 |
| 8236 | 62 function [cout, lev] = contourc (varargin) |
| 6257 | 63 |
| 64 if (nargin == 1) | |
| 65 vn = 10; | |
| 66 z = varargin{1}; | |
| 67 elseif (nargin == 2) | |
| 68 vn = varargin{2}; | |
| 69 z = varargin{1}; | |
| 7327 | 70 [nr, nc] = size (z); |
| 71 x = 1:nc; | |
| 72 y = 1:nr; | |
| 6257 | 73 elseif (nargin == 3) |
| 74 vn = 10; | |
| 75 x = varargin{1}; | |
| 76 y = varargin{2}; | |
| 77 z = varargin{3}; | |
| 78 elseif (nargin == 4) | |
| 79 vn = varargin{4}; | |
| 80 x = varargin{1}; | |
| 81 y = varargin{2}; | |
| 82 z = varargin{3}; | |
| 83 else | |
| 84 print_usage (); | |
| 85 endif | |
| 86 | |
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87 if (!ismatrix (z) || isvector (z) || isscalar (z)) |
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88 error ("contourc: z argument must be a matrix"); |
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89 endif |
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90 |
| 6257 | 91 if (isscalar (vn)) |
| 92 vv = linspace (min (z(:)), max (z(:)), vn+2)(2:end-1); | |
| 93 else | |
| 94 vv = unique (sort (vn)); | |
| 95 endif | |
| 96 | |
| 7327 | 97 if (isvector (x) && isvector (y)) |
| 98 c = __contourc__ (x(:)', y(:)', z, vv); | |
| 99 else | |
| 100 ## Indexes x,y for the purpose of __contourc__. | |
| 101 ii = 1:size (z,2); | |
| 102 jj = 1:size (z,1); | |
| 103 | |
| 104 ## Now call __contourc__ for the real work... | |
| 105 c = __contourc__ (ii, jj, z, vv); | |
| 106 | |
| 107 ## Map the contour lines from index space (i,j) back | |
| 108 ## to the original grid (x,y) | |
| 109 i = 1; | |
| 6257 | 110 |
| 7327 | 111 while (i < size (c,2)) |
| 112 clen = c(2, i); | |
| 113 ind = i + [1 : clen]; | |
| 6257 | 114 |
| 7327 | 115 ci = c(1, ind); |
| 116 cj = c(2,ind); | |
| 117 | |
| 118 ## due to rounding errors some elements of ci and cj | |
| 119 ## can fall out of the range of ii and jj and interp2 would | |
| 120 ## return NA for those values. | |
| 121 ## The permitted range is enforced here: | |
| 122 | |
| 123 ci = max (ci, 1); ci = min (ci, size (z, 2)); | |
| 124 cj = max (cj, 1); cj = min (cj, size (z, 1)); | |
| 125 | |
| 126 c(1, ind) = interp2 (ii, jj, x, ci, cj); | |
| 127 c(2, ind) = interp2 (ii, jj, y, ci, cj); | |
| 128 | |
| 129 i = i + clen + 1; | |
| 130 endwhile | |
| 6257 | 131 endif |
| 7327 | 132 |
| 8236 | 133 if (nargout > 0) |
| 134 cout = c; | |
| 6257 | 135 lev = vv; |
| 136 endif | |
| 137 | |
| 138 endfunction | |
| 7245 | 139 |
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140 %!test |
| 7245 | 141 %! x = 0:2; |
| 142 %! y = x; | |
| 143 %! z = x' * y; | |
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144 %! [c_actual, lev_actual]= contourc (x, y, z, 2:3); |
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145 %! c_expected = [2, 1, 1, 2, 2, 3, 1.5, 2; 4, 2, 2, 1, 1, 2, 2, 1.5]; |
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146 %! lev_expected = [2 3]; |
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147 %! assert (c_actual, c_expected, eps) |
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148 %! assert (lev_actual, lev_expected, eps) |
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149 |
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150 |