Mercurial > hg > octave-lyh
annotate scripts/general/shiftdim.m @ 12575:d0b799dafede
Grammarcheck files for 3.4.1 release.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Mon, 04 Apr 2011 15:33:46 -0700 |
| parents | fd0a3ac60b0e |
| children | 4d777e05d47c |
| rev | line source |
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| 11523 | 1 ## Copyright (C) 2004-2011 John Eaton and David Bateman |
| 4894 | 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. | |
| 4894 | 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/>. | |
| 4894 | 18 |
| 19 ## -*- texinfo -*- | |
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20 ## @deftypefn {Function File} {@var{y} =} shiftdim (@var{x}, @var{n}) |
| 6547 | 21 ## @deftypefnx {Function File} {[@var{y}, @var{ns}] =} shiftdim (@var{x}) |
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22 ## Shift the dimension of @var{x} by @var{n}, where @var{n} must be |
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23 ## an integer scalar. When @var{n} is positive, the dimensions of |
| 4894 | 24 ## @var{x} are shifted to the left, with the leading dimensions |
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25 ## circulated to the end. If @var{n} is negative, then the dimensions |
| 5539 | 26 ## of @var{x} are shifted to the right, with @var{n} leading singleton |
| 4894 | 27 ## dimensions added. |
| 28 ## | |
| 29 ## Called with a single argument, @code{shiftdim}, removes the leading | |
| 30 ## singleton dimensions, returning the number of dimensions removed | |
| 31 ## in the second output argument @var{ns}. | |
| 32 ## | |
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33 ## For example: |
| 4894 | 34 ## |
| 35 ## @example | |
| 36 ## @group | |
| 37 ## x = ones (1, 2, 3); | |
| 38 ## size (shiftdim (x, -1)) | |
| 5984 | 39 ## @result{} [1, 1, 2, 3] |
| 4894 | 40 ## size (shiftdim (x, 1)) |
| 5984 | 41 ## @result{} [2, 3] |
| 4894 | 42 ## [b, ns] = shiftdim (x); |
| 43 ## @result{} b = [1, 1, 1; 1, 1, 1] | |
| 44 ## @result{} ns = 1 | |
| 45 ## @end group | |
| 46 ## @end example | |
| 5642 | 47 ## @seealso {reshape, permute, ipermute, circshift, squeeze} |
| 4894 | 48 ## @end deftypefn |
| 49 | |
| 50 function [y, ns] = shiftdim (x, n) | |
| 51 | |
| 5518 | 52 if (nargin < 1 || nargin > 2) |
| 6046 | 53 print_usage (); |
| 5518 | 54 endif |
| 55 | |
| 56 nd = ndims (x); | |
| 57 orig_dims = size (x); | |
| 58 | |
| 4894 | 59 if (nargin == 1) |
| 4895 | 60 ## Find the first singleton dimension. |
| 5518 | 61 n = 0; |
| 62 while (n < nd && orig_dims(n+1) == 1) | |
| 63 n++; | |
| 4894 | 64 endwhile |
| 5518 | 65 endif |
| 66 | |
| 67 if (! isscalar (n) || floor (n) != n) | |
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68 error ("shiftdim: N must be a scalar integer"); |
| 5518 | 69 endif |
| 70 | |
| 71 if (n >= nd) | |
| 72 n = rem (n, nd); | |
| 73 endif | |
| 74 | |
| 75 if (n < 0) | |
| 76 singleton_dims = ones (1, -n); | |
| 77 y = reshape (x, [singleton_dims, orig_dims]); | |
| 78 elseif (n > 0) | |
| 5984 | 79 ## We need permute here instead of reshape to shift values in a |
| 80 ## compatible way. | |
| 81 y = permute (x, [n+1:ndims(x) 1:n]); | |
| 4894 | 82 else |
| 5518 | 83 y = x; |
| 4894 | 84 endif |
| 5518 | 85 |
| 86 ns = n; | |
| 87 | |
| 4894 | 88 endfunction |