--- /dev/null
+## Copyright (C) 2007-2012 David Bateman
+## Copyright (C) 2003 Alberto Terruzzi
+##
+## 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} {} pareto (@var{x})
+## @deftypefnx {Function File} {} pareto (@var{x}, @var{y})
+## @deftypefnx {Function File} {} pareto (@var{h}, @dots{})
+## @deftypefnx {Function File} {@var{h} =} pareto (@dots{})
+## Draw a Pareto chart, also called ABC chart. A Pareto chart is a bar graph
+## used to arrange information in such a way that priorities for process
+## improvement can be established. It organizes and displays information
+## to show the relative importance of data. The chart is similar to the
+## histogram or bar chart, except that the bars are arranged in decreasing
+## order from left to right along the abscissa.
+##
+## The fundamental idea (Pareto principle) behind the use of Pareto
+## diagrams is that the majority of an effect is due to a small subset of the
+## causes, so for quality improvement the first few (as presented on the
+## diagram) contributing causes to a problem usually account for the majority
+## of the result. Thus, targeting these "major causes" for elimination
+## results in the most cost-effective improvement scheme.
+##
+## The data are passed as @var{x} and the abscissa as @var{y}. If @var{y} is
+## absent, then the abscissa are assumed to be @code{1 : length (@var{x})}.
+## @var{y} can be a string array, a cell array of strings or a numerical
+## vector.
+##
+## The optional return value @var{h} is a 2-element vector with a graphics
+## handle for the created bar plot and a second handle for the created line
+## plot.
+##
+## An example of the use of @code{pareto} is
+##
+## @example
+## @group
+## Cheese = @{"Cheddar", "Swiss", "Camembert", ...
+## "Munster", "Stilton", "Blue"@};
+## Sold = [105, 30, 70, 10, 15, 20];
+## pareto (Sold, Cheese);
+## @end group
+## @end example
+## @end deftypefn
+
+function h = pareto (varargin)
+
+ if (nargin != 1 && nargin != 2)
+ print_usage ();
+ endif
+
+ x = varargin {1}(:).';
+ if (nargin == 2)
+ y = varargin {2}(:).';
+ if (! iscell (y))
+ if (ischar (y))
+ y = cellstr (y);
+ else
+ y = cellfun ("num2str", num2cell (y), "uniformoutput", false);
+ endif
+ endif
+ else
+ y = cellfun ("int2str", num2cell (1 : numel(x)),
+ "uniformoutput", false);
+ endif
+
+ [x, idx] = sort (x, "descend");
+ y = y (idx);
+ cdf = cumsum (x);
+ maxcdf = max(cdf);
+ cdf = cdf ./ maxcdf;
+ cdf95 = cdf - 0.95;
+ idx95 = find(sign(cdf95(1:end-1)) != sign(cdf95(2:end)))(1);
+
+ [ax, hbar, hline] = plotyy (1 : idx95, x (1 : idx95),
+ 1 : length(cdf), 100 .* cdf,
+ @bar, @plot);
+
+ axis (ax(1), [1 - 0.6, idx95 + 0.6, 0, maxcdf]);
+ axis (ax(2), [1 - 0.6, idx95 + 0.6, 0, 100]);
+ set (ax(2), "ytick", [0, 20, 40, 60, 80, 100],
+ "yticklabel", {"0%", "20%", "40%", "60%", "80%", "100%"});
+ set (ax(1), "xtick", 1 : idx95, "xticklabel", y (1: idx95));
+ set (ax(2), "xtick", 1 : idx95, "xticklabel", y (1: idx95));
+
+ if (nargout > 0)
+ h = [hbar; hline];
+ endif
+
+endfunction
+
+
+%!demo
+%! clf
+%! colormap (jet (64));
+%! Cheese = {"Cheddar", "Swiss", "Camembert", "Munster", "Stilton", "Blue"};
+%! Sold = [105, 30, 70, 10, 15, 20];
+%! pareto (Sold, Cheese);
+
+%!demo
+%! clf
+%! % Suppose that we want establish which products makes 80 % of turnover.
+%! Codes = {"AB4","BD7","CF8","CC5","AD11","BB5","BB3","AD8","DF3","DE7"};
+%! Value = [2.35 7.9 2.45 1.1 0.15 13.45 5.4 2.05 0.85 1.65]';
+%! SoldUnits = [54723 41114 16939 1576091 168000 687197 120222 168195, ...
+%! 1084118 55576]';
+%! pareto (Value.*SoldUnits, Codes);
+