demosm1.m

神经网络学习过程的实例程序

%% A One-dimensional Self-organizing Map
% Neurons in a 2-D layer learn to represent different regions of the input space
% where input vectors occur.  In addition, neighboring neurons learn to respond
% to similar inputs, thus the layer learns the topology of the presented input
% space.
%
% Copyright 1992-2002 The MathWorks, Inc.
% $Revision: 1.20 $  $Date: 2002/04/14 21:28:28 $

%%
% Here 100 data points are created on the unit circle.
%
% A competitive network will be used to classify these points into natural
% classes.

angles = 0:0.5*pi/99:0.5*pi;
P = [sin(angles); cos(angles)];
plot(P(1,:),P(2,:),'+r')

%%
% The map will be a 1-dimensional layer of 10 neurons.
%
% The first argument specifies two inputs, each with a range of 0 to 1.  The
% second determines the network is one dimensional with 10 neurons.

net = newsom([0 1;0 1],[10]);

%%
% Specify the network is to be trained for 10 epochs and use TRAIN to train the
% network on the input data P:

net.trainParam.epochs = 10;
net = train(net,P);

%%
% Now plot the trained network with PLOTSOM.
% 
% The red dots are the neuron's weight vectors, and the blue lines connect each
% pair within a distance of 1.

plotsom(net.iw{1,1},net.layers{1}.distances)

%%
% The map can now be used to classify inputs, like [1; 0]:
%
% Either neuron 1 or 10 should have an output of 1, as the above input vector
% was at one end of the presented input space.  The first pair of numbers
% indicate the neuron, and the single number indicates its output.

p = [1;0];
a = sim(net,p)