## Copyright (C) 1995, 1996, 1997, 1998, 2000, 2002, 2004, 2005, 2006,
##               2007, 2009 Friedrich Leisch
##
## 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} {} run_count (@var{x}, @var{n})
## Count the upward runs along the first non-singleton dimension of
## @var{x} of length 1, 2, @dots{}, @var{n}-1 and greater than or equal 
## to @var{n}.  If the optional argument @var{dim} is given then operate
## along this dimension.
## @end deftypefn

## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at>
## Description: Count upward runs

function retval = run_count (x, n, dim)

  if (nargin != 2 && nargin != 3)
    print_usage ();
  endif

  if (!ismatrix(x) || ischar(x))
    error ("run_count: X must be a numeric matrix or vector");
  endif

  if (!(isscalar (n) && n == round (n)) || n < 1)
    error ("run_count: N must be a positive integer");
  endif
  
  nd = ndims (x);
  sz = size (x);
  if (nargin != 3)
    ## Find the first non-singleton dimension.
    dim = find (sz > 1, 1);
    if (isempty (dim))
      dim = 1;
    endif
  else
    if (!(isscalar (dim) && dim == round (dim)) || 
        !(1 <= dim && dim <= nd))
      error ("run_count: DIM must be an integer and a valid dimension");
    endif
  endif

  if (dim != 1)
    perm = [1 : nd];
    perm(1) = dim;
    perm(dim) = 1;
    x = permute (x, perm);
  endif

  sz = size (x);
  idx = cell ();
  for i = 1 : nd
    idx{i} = 1 : sz(i);
  endfor
  c = sz(1); 
  tmp = zeros ([c + 1, sz(2 : end)]);
  infvec = Inf ([1, sz(2 : end)]);

  ind = find (diff ([infvec; x; -infvec]) < 0);
  tmp(ind(2:end) - 1) = diff(ind);
  tmp = tmp(idx{:});

  sz(1) = n;
  retval = zeros (sz);
  for k = 1 : (n-1)
    idx{1} = k;
    retval(idx{:}) = sum (tmp == k);
  endfor
  idx{1} = n;
  retval (idx{:}) = sum (tmp >= n);

  if (dim != 1)
    retval = ipermute (retval, perm);
  endif

endfunction