/netlab3.3/demprior.m

function demprior(action);

%DEMPRIOR Demonstrate sampling from a multi-parameter Gaussian prior.

%

%	Description

%	This function plots the functions represented by a multi-layer

%	perceptron network when the weights are set to values drawn from a

%	Gaussian prior distribution. The parameters AW1, AB1 AW2 and AB2

%	control the inverse variances of the first-layer weights, the hidden

%	unit  biases, the second-layer weights and the output unit biases

%	respectively.  Their values can be adjusted on a logarithmic scale

%	using the sliders, or  by typing values into the text boxes and

%	pressing the return key.

%

%	See also

%	MLP

%



%	Copyright (c) Ian T Nabney (1996-2001)



if nargin<1,

    action='initialize';

end;



if strcmp(action,'initialize')

  

  aw1 = 0.01;

  ab1 = 0.1;

  aw2 = 1.0;

  ab2 = 1.0;

  

  % Create FIGURE

  fig=figure( ...

    'Name','Sampling from a Gaussian prior', ...

    'Position', [50 50 480 380], ...

    'NumberTitle','off', ...

    'Color', [0.8 0.8 0.8], ...

    'Visible','on');



  % The TITLE BAR frame

  uicontrol(fig,  ...

    'Style','frame', ...

    'Units','normalized', ...

    'HorizontalAlignment', 'center', ...

    'Position', [0.5 0.82 0.45 0.1], ...

    'BackgroundColor',[0.60 0.60 0.60]);

  

  % The TITLE BAR text

  uicontrol(fig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.54 0.85 0.40 0.05], ...

    'HorizontalAlignment', 'left', ...

    'String', 'Sampling from a Gaussian prior');

  

  % Frames to enclose sliders

  uicontrol(fig, ...

    'Style', 'frame', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.05 0.08 0.35 0.18]);

  

  uicontrol(fig, ...

    'Style', 'frame', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.05 0.3 0.35 0.18]);

   

  uicontrol(fig, ...

    'Style', 'frame', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.05 0.52 0.35 0.18]);

   

  uicontrol(fig, ...

    'Style', 'frame', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.05 0.74 0.35 0.18]);

   

  % Frame text

  uicontrol(fig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'HorizontalAlignment', 'left', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.07 0.17 0.06 0.07], ...

    'String', 'aw1');



  % Frame text

  uicontrol(fig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'HorizontalAlignment', 'left', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.07 0.39 0.06 0.07], ...

    'String', 'ab1');



  % Frame text

  uicontrol(fig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'HorizontalAlignment', 'left', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.07 0.61 0.06 0.07], ...

    'String', 'aw2');



  % Frame text

  uicontrol(fig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'HorizontalAlignment', 'left', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.07 0.83 0.06 0.07], ...

    'String', 'ab2');

   

  % Slider

  minval = -5; maxval = 5;

  aw1slide = uicontrol(fig, ...

    'Style', 'slider', ...

    'Units', 'normalized', ...

    'Value', log10(aw1), ...

    'BackgroundColor', [0.8 0.8 0.8], ...

    'Position', [0.07 0.1 0.31 0.05], ...

    'Min', minval, 'Max', maxval, ...

    'Callback', 'demprior update');

  

  % Slider

  ab1slide = uicontrol(fig, ...

    'Style', 'slider', ...

    'Units', 'normalized', ...

    'Value', log10(ab1), ...

    'BackgroundColor', [0.8 0.8 0.8], ...

    'Position', [0.07 0.32 0.31 0.05], ...

    'Min', minval, 'Max', maxval, ...

    'Callback', 'demprior update');

  

  % Slider

  aw2slide = uicontrol(fig, ...

    'Style', 'slider', ...

    'Units', 'normalized', ...

    'Value', log10(aw2), ...

    'BackgroundColor', [0.8 0.8 0.8], ...

    'Position', [0.07 0.54 0.31 0.05], ...

    'Min', minval, 'Max', maxval, ...

    'Callback', 'demprior update');

  

  % Slider

  ab2slide = uicontrol(fig, ...

    'Style', 'slider', ...

    'Units', 'normalized', ...

    'Value', log10(ab2), ...

    'BackgroundColor', [0.8 0.8 0.8], ...

    'Position', [0.07 0.76 0.31 0.05], ...

    'Min', minval, 'Max', maxval, ...

    'Callback', 'demprior update');

  

  % The graph box

  haxes = axes('Position', [0.5 0.28 0.45 0.45], ...

    'Units', 'normalized', ...

    'Visible', 'on');

  

  % Text display of hyper-parameter values

  

  format = '%8f';

  

  aw1val = uicontrol(fig, ...

    'Style', 'edit', ...

    'Units', 'normalized', ...

    'Position', [0.15 0.17 0.23 0.07], ...

    'String', sprintf(format, aw1), ...

    'Callback', 'demprior newval');

  

  ab1val = uicontrol(fig, ...

    'Style', 'edit', ...

    'Units', 'normalized', ...

    'Position', [0.15 0.39 0.23 0.07], ...

    'String', sprintf(format, ab1), ...

    'Callback', 'demprior newval');

  

  aw2val = uicontrol(fig, ...

    'Style', 'edit', ...

    'Units', 'normalized', ...

    'Position', [0.15 0.61 0.23 0.07], ...

    'String', sprintf(format, aw2), ...

    'Callback', 'demprior newval');

  

  ab2val = uicontrol(fig, ...

    'Style', 'edit', ...

    'Units', 'normalized', ...

    'Position', [0.15 0.83 0.23 0.07], ...

    'String', sprintf(format, ab2), ...

    'Callback', 'demprior newval');

   

  % The SAMPLE button

  uicontrol(fig, ...

    'Style','push', ...

    'Units','normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position',[0.5 0.08 0.13 0.1], ...

    'String','Sample', ...

    'Callback','demprior replot');

  

  % The CLOSE button

  uicontrol(fig, ...

    'Style','push', ...

    'Units','normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position',[0.82 0.08 0.13 0.1], ...

    'String','Close', ...

    'Callback','close(gcf)');

  

  % The HELP button

  uicontrol(fig, ...

    'Style','push', ...

    'Units','normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position',[0.66 0.08 0.13 0.1], ...

    'String','Help', ...

    'Callback','demprior help');

  

   % Save handles to objects

  

  hndlList=[fig aw1slide ab1slide aw2slide ab2slide aw1val ab1val aw2val ...

      ab2val haxes];

  set(fig, 'UserData', hndlList);

  

  demprior('replot')

  

  

elseif strcmp(action, 'update'),

  

  % Update when a slider is moved.

  

  hndlList   = get(gcf, 'UserData');

  aw1slide   = hndlList(2);

  ab1slide = hndlList(3);

  aw2slide  = hndlList(4);

  ab2slide = hndlList(5);

  aw1val = hndlList(6);

  ab1val = hndlList(7);

  aw2val = hndlList(8);

  ab2val = hndlList(9);

  haxes = hndlList(10);

  

  aw1 = 10^get(aw1slide, 'Value');

  ab1 = 10^get(ab1slide, 'Value');

  aw2 = 10^get(aw2slide, 'Value');

  ab2 = 10^get(ab2slide, 'Value');

    

  format = '%8f';

  set(aw1val, 'String', sprintf(format, aw1));

  set(ab1val, 'String', sprintf(format, ab1));

  set(aw2val, 'String', sprintf(format, aw2));

  set(ab2val, 'String', sprintf(format, ab2));

  

  demprior('replot');

  

elseif strcmp(action, 'newval'),

  

  % Update when text is changed.

  

  hndlList   = get(gcf, 'UserData');

  aw1slide   = hndlList(2);

  ab1slide = hndlList(3);

  aw2slide  = hndlList(4);

  ab2slide = hndlList(5);

  aw1val = hndlList(6);

  ab1val = hndlList(7);

  aw2val = hndlList(8);

  ab2val = hndlList(9);

  haxes = hndlList(10);

    

  aw1 = sscanf(get(aw1val, 'String'), '%f');

  ab1 = sscanf(get(ab1val, 'String'), '%f');

  aw2 = sscanf(get(aw2val, 'String'), '%f');

  ab2 = sscanf(get(ab2val, 'String'), '%f');

  

  set(aw1slide, 'Value', log10(aw1));

  set(ab1slide, 'Value', log10(ab1));

  set(aw2slide, 'Value', log10(aw2));

  set(ab2slide, 'Value', log10(ab2));

  

  demprior('replot');

  

elseif strcmp(action, 'replot'),

  

  % Re-sample from the prior and plot graphs.

 

  oldFigNumber=watchon;



  hndlList   = get(gcf, 'UserData');

  aw1slide   = hndlList(2);

  ab1slide = hndlList(3);

  aw2slide  = hndlList(4);

  ab2slide = hndlList(5);

  haxes = hndlList(10);

  

  aw1 = 10^get(aw1slide, 'Value');

  ab1 = 10^get(ab1slide, 'Value');

  aw2 = 10^get(aw2slide, 'Value');

  ab2 = 10^get(ab2slide, 'Value');

 

  axes(haxes);

  cla

  set(gca, ...

    'Box', 'on', ...

    'Color', [0 0 0], ...

    'XColor', [0 0 0], ...

    'YColor', [0 0 0], ...

    'FontSize', 14);

  axis([-1 1 -10 10]);  

  set(gca,'DefaultLineLineWidth', 2);



  nhidden = 12;

  prior = mlpprior(1, nhidden, 1, aw1, ab1, aw2, ab2);

  xvals = -1:0.005:1;

  nsample = 10;    % Number of samples from prior.

  hold on

  plot([-1 0; 1 0], [0 -10; 0 10], 'b--');

  net = mlp(1, nhidden, 1, 'linear', prior);

  for i = 1:nsample

    net = mlpinit(net, prior);

    yvals = mlpfwd(net, xvals');

    plot(xvals', yvals, 'y');

  end

    

  watchoff(oldFigNumber);

 

elseif strcmp(action, 'help'),

  

  % Provide help to user.



  oldFigNumber=watchon;



  helpfig = figure('Position', [100 100 480 400], ...

    'Name', 'Help', ...

    'NumberTitle', 'off', ...

    'Color', [0.8 0.8 0.8], ...

    'Visible','on');

  

    % The HELP TITLE BAR frame

  uicontrol(helpfig,  ...

    'Style','frame', ...

    'Units','normalized', ...

    'HorizontalAlignment', 'center', ...

    'Position', [0.05 0.82 0.9 0.1], ...

    'BackgroundColor',[0.60 0.60 0.60]);

  

  % The HELP TITLE BAR text

  uicontrol(helpfig, ...

    'Style', 'text', ...

    'Units', 'normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position', [0.26 0.85 0.6 0.05], ...

    'HorizontalAlignment', 'left', ...

    'String', 'Help: Sampling from a Gaussian Prior');

  

  helpstr1 = strcat( ...

    'This demonstration shows the effects of sampling from a Gaussian', ...

     ' prior over weights for a two-layer feed-forward network. The', ...

     ' parameters aw1, ab1, aw2 and ab2 control the inverse variances of', ...

     ' the first-layer weights, the hidden unit biases, the second-layer', ...

     ' weights and the output unit biases respectively. Their values can', ...

     ' be adjusted on a logarithmic scale using the sliders, or by', ...

     ' typing values into the text boxes and pressing the return key.', ...

     '  After setting these values, press the ''Sample'' button to see a', ...

     ' new sample from the prior. ');

   helpstr2 = strcat( ...

     'Observe how aw1 controls the horizontal length-scale of the', ...

     ' variation in the functions, ab1 controls the input range over', ...

     ' such variations occur, aw2 sets the vertical scale of the output', ...

     ' and ab2 sets the vertical off-set of the output. The network has', ...

     ' 12 hidden units. ');

   hstr(1) = {helpstr1};

   hstr(2) = {''};

   hstr(3) = {helpstr2};



  % The HELP text

  helpui = uicontrol(helpfig, ...

    'Style', 'edit', ...

    'Units', 'normalized', ...

    'ForegroundColor', [0 0 0], ...

    'HorizontalAlignment', 'left', ...

    'BackgroundColor', [1 1 1], ...

    'Min', 0, ...

    'Max', 2, ...

    'Position', [0.05 0.2 0.9 0.8]);

   

   [hstrw , newpos] = textwrap(helpui, hstr, 70);

   set(helpui, 'String', hstrw, 'Position', [0.05, 0.2, 0.9, newpos(4)]);

   

   

  % The CLOSE button

  uicontrol(helpfig, ...

    'Style','push', ...

    'Units','normalized', ...

    'BackgroundColor', [0.6 0.6 0.6], ...

    'Position',[0.4 0.05 0.2 0.1], ...

    'String','Close', ...

    'Callback','close(gcf)');



   watchoff(oldFigNumber);



end;



end