ranks.m

GNU Octave is a high-level language, primarily intended for numerical computations. It provides a c

## Copyright (C) 1995, 1996, 1997  Kurt Hornik
## 
## 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 2, 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 file.  If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

## usage:  ranks (x)
##
## If x is a vector, return the (column) vector of ranks of x adjusted
## for ties.  
## If x is a matrix, do the above for each column of x.
  
## Author:  KH <[e-mail]>
## Description:  Compute ranks

## This code is rather ugly, but is there an easy way to get the ranks
## adjusted for ties from sort?
  
function y = ranks (x)

  if (nargin != 1)
    usage ("ranks (x)");
  endif
  
  y = [];

  [r, c] = size (x);
  if ((r == 1) && (c > 0))
    p = x' * ones (1, c);
    y = sum (p < p') + (sum (p == p') + 1) / 2;
  elseif (r > 1)
    o = ones (1, r);
    for i = 1 : c;
      p = x (:, i) * o;
      y = [y, ( sum (p < p') + (sum (p == p') + 1) / 2 )'];
    endfor
  endif
  
endfunction