update packages

[CreaPhase.git] / octave_packages / m / strings / strtrunc.m

diff --git a/octave_packages/m/strings/strtrunc.m b/octave_packages/m/strings/strtrunc.m
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+## Copyright (C) 2006-2012 William Poetra Yoga Hadisoeseno
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} strtrunc (@var{s}, @var{n})
+## Truncate the character string @var{s} to length @var{n}.  If @var{s}
+## is a character matrix, then the number of columns is adjusted.
+## If @var{s} is a cell array of strings, then the operation is performed
+## on each cell element and the new cell array is returned.
+## @end deftypefn
+
+function s = strtrunc (s, n)
+
+  if (nargin != 2)
+    print_usage ();
+  endif
+
+  n = fix (n);
+  if (! isscalar (n) || n < 0)
+    error ("strtrunc: length N must be a positive integer (N >= 0)");
+  endif
+
+  if (ischar (s))
+    if (n < columns (s))
+      s = s(:, 1:n);
+    endif
+  elseif (iscellstr (s))
+    ## Convoluted approach converts cellstr to char matrix, trims the character
+    ## matrix using indexing, and then converts back to cellstr with mat2cell.
+    ## This approach is 24X faster than using cellfun with call to strtrunc
+    idx = cellfun ("size", s, 2) > n;
+    rows = cellfun ("size", s(idx), 1);
+    if (! isempty (rows))
+      s(idx) = mat2cell (char (s(idx))(:, 1:n), rows);
+    endif
+  else
+    error ("strtrunc: S must be a character string or a cell array of strings");
+  endif
+
+endfunction
+
+
+%!assert (strtrunc("abcdefg", 4), "abcd");
+%!assert (strtrunc("abcdefg", 10), "abcdefg");
+%!assert (strtrunc(char ("abcdef", "fedcba"), 3), ["abc"; "fed"]);
+%!assert (strtrunc({"abcdef", "fedcba"}, 3), {"abc", "fed"});
+%!assert (strtrunc({"", "1", "21", "321"}, 1), {"", "1", "2", "3"})
+%!assert (strtrunc({"1", "", "2"}, 1), {"1", "", "2"})
+%!test
+%! cstr = {"line1"; ["line2"; "line3"]; "line4"};
+%! y = strtrunc (cstr, 4);
+%! assert (size (y), [3, 1]); 
+%! assert (size (y{2}), [2, 4]); 
+%! assert (y{2}, repmat ("line", 2, 1));
+
+%% Test input validation
+%!error strtrunc ()
+%!error strtrunc ("abcd")
+%!error strtrunc ("abcd", 4, 5)
+%!error <N must be a positive integer> strtrunc ("abcd", ones (2,2))
+%!error <N must be a positive integer> strtrunc ("abcd", -1)
+%!error <S must be a character string or a cell array of strings> strtrunc (1, 1)
+