Mercurial > hg > octave-lojdl
changeset 13277:9f2e568123ea
circshift.m: Recode to do away with some for loops.
* circshift.m: Use colon indexing to do away with some for loops.
Improve input validation and add tests for it.
author | Rik <octave@nomad.inbox5.com> |
---|---|
date | Wed, 05 Oct 2011 11:43:05 -0700 |
parents | d5c8c2fe2eed |
children | 04edb15d7966 |
files | scripts/general/circshift.m |
diffstat | 1 files changed, 45 insertions(+), 40 deletions(-) [+] |
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line diff
--- a/scripts/general/circshift.m +++ b/scripts/general/circshift.m @@ -47,53 +47,58 @@ function y = circshift (x, n) - if (nargin == 2) - if (isempty (x)) - y = x; - else - nd = ndims (x); - sz = size (x); - - if (! isvector (n) && length (n) > nd) - error ("circshift: N must be a vector, no longer than the number of dimension in X"); - endif - - if (any (n != floor (n))) - error ("circshift: all values of N must be integers"); - endif - - idx = cell (); - for i = 1:length (n); - nn = n(i); - if (nn < 0) - while (sz(i) <= -nn) - nn = nn + sz(i); - endwhile - idx{i} = [(1-nn):sz(i), 1:-nn]; - else - while (sz(i) <= nn) - nn = nn - sz(i); - endwhile - idx{i} = [(sz(i)-nn+1):sz(i), 1:(sz(i)-nn)]; - endif - endfor - for i = (length(n) + 1) : nd - idx{i} = 1:sz(i); - endfor - y = x(idx{:}); - endif - else + if (nargin != 2) print_usage (); endif + + if (isempty (x)) + y = x; + return; + endif + + nd = ndims (x); + sz = size (x); + + if (! isvector (n) || length (n) > nd) + error ("circshift: N must be a vector, no longer than the number of dimension in X"); + elseif (any (n != fix (n))) + error ("circshift: all values of N must be integers"); + endif + + idx = repmat ({':'}, 1, nd); + for i = 1:length (n); + b = n(i); + d = sz(i); + if (b > 0) + b = rem (b, d); + idx{i} = [d-b+1:d, 1:d-b]; + elseif (b < 0) + b = rem (abs (b), d); + idx{i} = [b+1:d, 1:b]; + endif + endfor + + y = x(idx{:}); + endfunction + %!shared x %! x = [1, 2, 3; 4, 5, 6; 7, 8, 9]; %!assert (circshift (x, 1), [7, 8, 9; 1, 2, 3; 4, 5, 6]) %!assert (circshift (x, -2), [7, 8, 9; 1, 2, 3; 4, 5, 6]) -%!assert (circshift (x, [0, 1]), [3, 1, 2; 6, 4, 5; 9, 7, 8]); -%!assert (circshift ([],1), []) +%!assert (circshift (x, [0, 1]), [3, 1, 2; 6, 4, 5; 9, 7, 8]) +%!assert (circshift ([], 1), []) + +%!assert (circshift (eye (3), 1), circshift (eye (3), 1)) +%!assert (circshift (eye (3), 1), [0,0,1;1,0,0;0,1,0]) -%!assert (full (circshift (eye (3), 1)), circshift (full (eye (3)), 1)) -%!assert (full (circshift (eye (3), 1)), [0,0,1;1,0,0;0,1,0]) +%% Test input validation +%!error circshift () +%!error circshift (1) +%!error circshift (1,2,3) +%!error circshift (1, ones(2,2)) +%!error circshift (1, [1 2 3]) +%!error circshift (1, 1.5) +