Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / statistics-1.1.3 / tabulate.m

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+## Copyright (C) 2003 Alberto Terruzzi <t-albert@libero.it>
+##
+## This program 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.
+##
+## This program 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
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{table} =} tabulate (@var{data}, @var{edges})
+##
+## Compute a frequency table.
+##
+## For vector data, the function counts the number of
+## values in data that fall between the elements in the edges vector
+## (which must contain monotonically non-decreasing values). @var{table} is a
+## matrix.
+## The first column of @var{table} is the number of bin, the second
+## is the number of instances in each class (absolute frequency). The
+## third column contains the percentage of each value (relative
+## frequency) and the fourth column contains the cumulative frequency.
+##
+## If @var{edges} is missed the width of each class is unitary, if @var{edges}
+## is a scalar then represent the number of classes, or you can define the
+## width of each bin.
+## @var{table}(@var{k}, 2) will count the value @var{data} (@var{i}) if 
+## @var{edges} (@var{k}) <= @var{data} (@var{i}) < @var{edges} (@var{k}+1).
+## The  last bin will count the value of @var{data} (@var{i}) if
+## @var{edges}(@var{k}) <= @var{data} (@var{i}) <=  @var{edges} (@var{k}+1).  
+## Values outside the values in @var{edges} are not counted.  Use -inf and inf
+## in @var{edges} to include all values. 
+## Tabulate with no output arguments returns a formatted table in the
+## command window. 
+##
+## Example
+##
+## @example
+## sphere_radius = [1:0.05:2.5];
+## tabulate (sphere_radius)
+## @end example
+##
+## Tabulate returns 2 bins, the first contains the sphere with radius
+## between 1 and 2 mm excluded, and the second one contains the sphere with
+## radius between 2 and 3 mm.
+##
+## @example
+## tabulate (sphere_radius, 10)
+## @end example
+##
+## Tabulate returns ten bins.
+##
+## @example
+## tabulate (sphere_radius, [1, 1.5, 2, 2.5])
+## @end example
+##
+## Tabulate returns three bins, the first contains the sphere with radius
+## between 1 and 1.5 mm excluded, the second one contains the sphere with
+## radius between 1.5 and 2 mm excluded, and the third contains the sphere with
+## radius between 2 and 2.5 mm. 
+##
+## @example
+## bar (table (:, 1), table (:, 2))
+## @end example
+##
+## draw histogram.
+##
+## @seealso{bar, pareto}
+## @end deftypefn
+
+## Author: Alberto Terruzzi <t-albert@libero.it>
+## Version: 1.0
+## Created: 13 February 2003
+
+function table = tabulate (varargin)
+
+  if nargin < 1 || nargin > 2
+    print_usage;
+  endif
+
+  data = varargin{1};
+  if isvector (data) != 1
+    error ("data must be a vector.");
+  endif
+  n = length(data);
+  m = min(data);
+  M = max(data);
+
+  if nargin == 1 edges = 1:1:max(data)+1;
+  else edges = varargin{2};
+  end 
+
+  if isscalar(edges)
+    h=(M-m)/edges;
+    edges = [m:h:M];
+  end
+
+  # number of classes
+  bins=length(edges)-1;
+  # initialize freqency table
+  freqtable = zeros(bins,4);
+
+  for k=1:1:bins;
+    if k != bins
+      freqtable(k,2)=length(find (data >= edges(k) & data < edges(k+1)));
+    else
+      freqtable(k,2)=length(find (data >= edges(k) & data <= edges(k+1)));
+    end
+    if k == 1 freqtable (k,4) = freqtable(k,2);
+    else freqtable(k,4) = freqtable(k-1,4) + freqtable(k,2); 
+    end
+  end
+
+  freqtable(:,1) = edges(1:end-1)(:);
+  freqtable(:,3) = 100*freqtable(:,2)/n;
+
+  if nargout == 0
+    disp("     bin     Fa       Fr%        Fc");
+    printf("%8g  %5d    %6.2f%%    %5d\n",freqtable');
+  else table = freqtable;
+  end
+
+endfunction