update packages

[CreaPhase.git] / octave_packages / m / statistics / distributions / discrete_rnd.m

diff --git a/octave_packages/m/statistics/distributions/discrete_rnd.m b/octave_packages/m/statistics/distributions/discrete_rnd.m
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+## Copyright (C) 2012 Rik Wehbring
+## Copyright (C) 1996-2012 Kurt Hornik
+##
+## 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} {} discrete_rnd (@var{v}, @var{p})
+## @deftypefnx {Function File} {} discrete_rnd (@var{v}, @var{p}, @var{r})
+## @deftypefnx {Function File} {} discrete_rnd (@var{v}, @var{p}, @var{r}, @var{c}, @dots{})
+## @deftypefnx {Function File} {} discrete_rnd (@var{v}, @var{p}, [@var{sz}])
+## Return a matrix of random samples from the univariate distribution which
+## assumes the values in @var{v} with probabilities @var{p}.
+##
+## When called with a single size argument, return a square matrix with
+## the dimension specified.  When called with more than one scalar argument the
+## first two arguments are taken as the number of rows and columns and any
+## further arguments specify additional matrix dimensions.  The size may also
+## be specified with a vector of dimensions @var{sz}.
+## 
+## If no size arguments are given then the result matrix is the common size of
+## @var{v} and @var{p}.
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: Random deviates from a discrete distribution
+
+function rnd = discrete_rnd (v, p, varargin)
+
+  if (nargin < 2)
+    print_usage ();
+  endif
+
+  if (! isvector (v))
+    error ("discrete_rnd: V must be a vector");
+  elseif (! isvector (p) || (length (p) != length (v)))
+    error ("discrete_rnd: P must be a vector with length (V) elements");
+  elseif (any (isnan (p)))
+    error ("discrete_rnd: P must not have any NaN elements");
+  elseif (! (all (p >= 0) && any (p)))
+    error ("discrete_rnd: P must be a nonzero, non-negative vector");
+  endif
+
+  if (nargin == 2)
+    sz = size (v);
+  elseif (nargin == 3)
+    if (isscalar (varargin{1}) && varargin{1} >= 0)
+      sz = [varargin{1}, varargin{1}];
+    elseif (isrow (varargin{1}) && all (varargin{1} >= 0))
+      sz = varargin{1};
+    else
+      error ("discrete_rnd: dimension vector must be row vector of non-negative integers");
+    endif
+  elseif (nargin > 3)
+    if (any (cellfun (@(x) (!isscalar (x) || x < 0), varargin)))
+      error ("discrete_rnd: dimensions must be non-negative integers");
+    endif
+    sz = [varargin{:}];
+  endif
+
+  rnd = v(lookup (cumsum (p(1:end-1)) / sum (p), rand (sz)) + 1);
+  rnd = reshape (rnd, sz);
+
+endfunction
+
+
+%!assert(size (discrete_rnd (1:2, 1:2, 3)), [3, 3]);
+%!assert(size (discrete_rnd (1:2, 1:2, [4 1])), [4, 1]);
+%!assert(size (discrete_rnd (1:2, 1:2, 4, 1)), [4, 1]);
+
+%% Test class of input preserved
+%!assert(class (discrete_rnd (1:2, 1:2)), "double");
+%!assert(class (discrete_rnd (single(1:2), 1:2)), "single");
+## FIXME: Maybe this should work, maybe it shouldn't.
+#%!assert(class (discrete_rnd (1:2, single(1:2))), "single");
+
+%% Test input validation
+%!error discrete_rnd ()
+%!error discrete_rnd (1)
+%!error discrete_rnd (1:2,1:2, -1)
+%!error discrete_rnd (1:2,1:2, ones(2))
+%!error discrete_rnd (1:2,1:2, [2 -1 2])
+%!error discrete_rnd (1:2,1:2, 1, ones(2))
+%!error discrete_rnd (1:2,1:2, 1, -1)
+%% test v,p verification
+%!error discrete_rnd (1, ones(2), ones(2,1))
+%!error discrete_rnd (1, ones(2,1), ones(1,1))
+%!error discrete_rnd (1, ones(2,1), [1 -1])
+%!error discrete_rnd (1, ones(2,1), [1 NaN])
+%!error discrete_rnd (1, ones(2,1), [0  0])
+