% 
% Written by:
% -- 
% John L. Weatherwax                2005-08-04
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
% Epage 169
% 
%-----

close all; clc; clear; 

% Lets plot the data: 
%
XB = [ -1.75, +1.5; -1.65, +1.; -1.5, -0.75; -0.5, 0.25; 0.7, -0.9; 1.2, -1.1]; % class B 
XA = [ -0.5, +0.8; 0, 0.3; 0.5, 0.75; 0.9, -1.3 ]; 

hA = plot( XA(:,1), XA(:,2), 'or' ); hold on; 
hB = plot( XB(:,1), XB(:,2), '.b' ); hold on; 
legend( [hA,hB], {'class +1 (A)', 'class -1 (B)'}, 'location', 'north' ); axis( [-3,+3,-3,+3] ); 

% Lets draw some decision regions: 
%
x1 = linspace( -3, +3, 50 ); 

% the line #1: 
x2 = -x1;
plot( x1, x2, 'k-' ); hold on; 
text( -2.7, 2.85, '1' ); 
text( -2.5, 2.4, '-' ); 
text( -2.5, 2.6, '+' ); 

% the line #2
x2 = x1;
plot( x1, x2, 'k-' ); 
text( 2.5, 2.75, '2' ); 
text( 2.1, 2.3, '+' ); 
text( 2.1, 2.1, '-' ); 

% the line #3
addpath('~/Matlab');
hline( -1, 'k-' );
text( -2.75, -0.9, '3' ); 
text( -2.6, -0.9, '+' ); 
text( -2.6, -1.1, '-' ); 

text( 0.9, -1.6, 'A_1' ); 
text( 1.35, -1.25, 'B_1' ); 

xlabel('x_1'); ylabel('x_2'); %grid on; 

fn = ['chap_4_tiling_example.eps'];
saveas(gcf,['../../WriteUp/Graphics/Chapter4/',fn],'epsc');