Use in-place operators in m-files where possible. * scripts/audio/@audioplayer/set.m, scripts/audio/@audiorecorder/set.m, scripts/audio/mu2lin.m, scripts/elfun/cosd.m, scripts/general/del2.m, scripts/general/profexplore.m, scripts/general/quadl.m, scripts/general/rat.m, scripts/general/rotdim.m, scripts/help/get_first_help_sentence.m, scripts/help/private/__strip_html_tags__.m, scripts/image/cubehelix.m, scripts/io/textread.m, scripts/linear-algebra/duplication_matrix.m, scripts/linear-algebra/housh.m, scripts/linear-algebra/krylov.m, scripts/linear-algebra/logm.m, scripts/linear-algebra/normest.m, scripts/linear-algebra/onenormest.m, scripts/optimization/fminsearch.m, scripts/optimization/lsqnonneg.m, scripts/optimization/qp.m, scripts/plot/appearance/annotation.m, scripts/plot/appearance/axis.m, scripts/plot/appearance/legend.m, scripts/plot/appearance/specular.m, scripts/plot/draw/colorbar.m, scripts/plot/draw/hist.m, scripts/plot/draw/plotmatrix.m, scripts/plot/draw/private/__stem__.m, scripts/plot/util/__actual_axis_position__.m, scripts/plot/util/__gnuplot_drawnow__.m, scripts/plot/util/findobj.m, scripts/plot/util/print.m, scripts/plot/util/private/__go_draw_axes__.m, scripts/plot/util/private/__print_parse_opts__.m, scripts/plot/util/rotate.m, scripts/polynomial/pchip.m, scripts/polynomial/polyaffine.m, scripts/polynomial/polyder.m, scripts/polynomial/private/__splinefit__.m, scripts/polynomial/residue.m, scripts/signal/arch_fit.m, scripts/signal/arch_rnd.m, scripts/signal/bartlett.m, scripts/signal/blackman.m, scripts/signal/freqz.m, scripts/signal/hamming.m, scripts/signal/hanning.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/signal/stft.m, scripts/sparse/bicgstab.m, scripts/sparse/cgs.m, scripts/sparse/private/__sprand_impl__.m, scripts/sparse/qmr.m, scripts/sparse/sprandsym.m, scripts/sparse/svds.m, scripts/specfun/legendre.m, scripts/special-matrix/gallery.m, scripts/statistics/base/gls.m, scripts/statistics/models/logistic_regression.m, scripts/statistics/tests/kruskal_wallis_test.m, scripts/statistics/tests/manova.m, scripts/statistics/tests/wilcoxon_test.m, scripts/time/datevec.m: Use in-place operators in m-files where possible.

## Copyright (C) 2005-2015 Paul Kienzle
##
## 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} {count =} runlength (@var{x})
## @deftypefnx {Function File} {[count, value] =} runlength (@var{x})
## Find the lengths of all sequences of common values.
##
## @var{count} is a vector with the lengths of each repeated value.
##
## The optional output @var{value} contains the value that was repeated in
## the sequence.
##
## @example
## @group
## runlength ([2, 2, 0, 4, 4, 4, 0, 1, 1, 1, 1])
## @result{}  [2, 1, 3, 1, 4]
## @end group
## @end example
## @seealso{run_count}
## @end deftypefn

function [count, value] = runlength (x)

  if (nargin != 1)
    print_usage ();
  endif

  if (! (isnumeric (x) || islogical (x)) || ! isvector (x))
    error ("runlength: X must be a numeric vector");
  endif

  if (iscolumn (x))
    x = x.';
  endif

  idx = [find(x(1:end-1) != x(2:end)), length(x)];
  count = diff ([0 idx]);
  if (nargout == 2)
    value = x(idx);
  endif

endfunction


%!assert (runlength ([2 2 0 4 4 4 0 1 1 1 1]), [2 1 3 1 4])
%!assert (runlength ([2 2 0 4 4 4 0 1 1 1 1]'), [2 1 3 1 4])
%!test
%! [c, v] = runlength ([2 2 0 4 4 4 0 1 1 1 1]);
%! assert (c, [2 1 3 1 4]);
%! assert (v, [2 0 4 0 1]);

## Test input validation
%!error runlength ()
%!error runlength (1, 2)
%!error runlength (['A'; 'B'])
%!error runlength (ones (2,2))