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infogain_seq.m

## Copyright (C) 2006 Joseph Wakeling <joseph.wakeling@webdrake.net>
## 
## 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 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} {} infogain_seq (@var{seq_x}, @var{seq_y})
##
## Gives the information gain ratio (also known as the
## `uncertainty coefficient') of the sequence x
## conditional on y:
##        I(X|Y) = I(X;Y)/H(X)
##
## @example
## @group
##          X=[1, 1, 2, 1, 1];
##          Y=[2, 2, 1, 1, 2];
##          infogain_seq(X,Y)
## @end group
## @end example
## @end deftypefn
## @seealso{infoentr_seq}
##
function IGR = infogain_seq(x,y)
if nargin!=2
      usage("infogain(x,y)")
endif

IGR = mutualinfo_seq(x,y)/infoentr_seq(x);

# Could also do
# IGR = 1 - condentr(x,y)/infoentr(x);
end
%!assert(infogain_seq([2, 2, 1, 1, 2],[2, 2, 1, 1, 2]),2,0)

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