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function sMap = som_randinit(D, varargin)
%SOM_RANDINIT Initialize a Self-Organizing Map with random values.
%
% sMap = som_randinit(D, [[argID,] value, ...])
%
% sMap = som_randinit(D);
% sMap = som_randinit(D,sMap);
% sMap = som_randinit(D,'munits',100,'hexa');
%
% Input and output arguments ([]'s are optional):
% D The training data.
% (struct) data struct
% (matrix) data matrix, size dlen x dim
% [argID, (string) Parameters affecting the map topology are given
% value] (varies) as argument ID - argument value pairs, listed below.
%
% sMap (struct) map struct
%
% Here are the valid argument IDs and corresponding values. The values
% which are unambiguous (marked with '*') can be given without the
% preceeding argID.
% 'munits' (scalar) number of map units
% 'msize' (vector) map size
% 'lattice' *(string) map lattice: 'hexa' or 'rect'
% 'shape' *(string) map shape: 'sheet', 'cyl' or 'toroid'
% 'topol' *(struct) topology struct
% 'som_topol','sTopol' = 'topol'
% 'map' *(struct) map struct
% 'som_map','sMap' = 'map'
%
% For more help, try 'type som_randinit' or check out online documentation.
% See also SOM_MAP_STRUCT, SOM_LININIT, SOM_MAKE.
%%%%%%%%%%%%% DETAILED DESCRIPTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% som_randinit
%
% PURPOSE
%
% Initializes a SOM with random values.
%
% SYNTAX
%
% sMap = som_randinit(D)
% sMap = som_randinit(D,sMap);
% sMap = som_randinit(D,'munits',100,'hexa');
%
% DESCRIPTION
%
% Initializes a SOM with random values. If necessary, a map struct
% is created first. For each component (xi), the values are uniformly
% distributed in the range of [min(xi) max(xi)].
%
% REQUIRED INPUT ARGUMENTS
%
% D The training data.
% (struct) Data struct. If this is given, its '.comp_names' and
% '.comp_norm' fields are copied to the map struct.
% (matrix) data matrix, size dlen x dim
%
% OPTIONAL INPUT ARGUMENTS
%
% argID (string) Argument identifier string (see below).
% value (varies) Value for the argument (see below).
%
% The optional arguments can be given as 'argID',value -pairs. If an
% argument is given value multiple times, the last one is used.
%
% Here are the valid argument IDs and corresponding values. The values
% which are unambiguous (marked with '*') can be given without the
% preceeding argID.
% 'dlen' (scalar) length of the training data
% 'data' (matrix) the training data
% *(struct) the training data
% 'munits' (scalar) number of map units
% 'msize' (vector) map size
% 'lattice' *(string) map lattice: 'hexa' or 'rect'
% 'shape' *(string) map shape: 'sheet', 'cyl' or 'toroid'
% 'topol' *(struct) topology struct
% 'som_topol','sTopol' = 'topol'
% 'map' *(struct) map struct
% 'som_map','sMap' = 'map'
%
% OUTPUT ARGUMENTS
%
% sMap (struct) The initialized map struct.
%
% EXAMPLES
%
% sMap = som_randinit(D);
% sMap = som_randinit(D,sMap);
% sMap = som_randinit(D,sTopol);
% sMap = som_randinit(D,'msize',[10 10]);
% sMap = som_randinit(D,'munits',100,'hexa');
%
% SEE ALSO
%
% som_map_struct Create a map struct.
% som_lininit Initialize a map using linear initialization algorithm.
% som_make Initialize and train self-organizing map.
% Copyright (c) 1997-2000 by the SOM toolbox programming team.
% http://www.cis.hut.fi/projects/somtoolbox/
% Version 1.0beta ecco 100997
% Version 2.0beta juuso 101199
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% check arguments
% data
if isstruct(D),
data_name = D.name;
comp_names = D.comp_names;
comp_norm = D.comp_norm;
D = D.data;
struct_mode = 1;
else
data_name = inputname(1);
struct_mode = 0;
end
[dlen dim] = size(D);
% varargin
sMap = [];
sTopol = som_topol_struct;
sTopol.msize = 0;
munits = NaN;
i=1;
while i<=length(varargin),
argok = 1;
if ischar(varargin{i}),
switch varargin{i},
case 'munits', i=i+1; munits = varargin{i}; sTopol.msize = 0;
case 'msize', i=i+1; sTopol.msize = varargin{i};
munits = prod(sTopol.msize);
case 'lattice', i=i+1; sTopol.lattice = varargin{i};
case 'shape', i=i+1; sTopol.shape = varargin{i};
case {'som_topol','sTopol','topol'}, i=i+1; sTopol = varargin{i};
case {'som_map','sMap','map'}, i=i+1; sMap = varargin{i}; sTopol = sMap.topol;
case {'hexa','rect'}, sTopol.lattice = varargin{i};
case {'sheet','cyl','toroid'}, sTopol.shape = varargin{i};
otherwise argok=0;
end
elseif isstruct(varargin{i}) & isfield(varargin{i},'type'),
switch varargin{i}.type,
case 'som_topol',
sTopol = varargin{i};
case 'som_map',
sMap = varargin{i};
sTopol = sMap.topol;
otherwise argok=0;
end
else
argok = 0;
end
if ~argok,
disp(['(som_topol_struct) Ignoring invalid argument #' num2str(i)]);
end
i = i+1;
end
if ~isempty(sMap),
[munits dim2] = size(sMap.codebook);
if dim2 ~= dim, error('Map and data must have the same dimension.'); end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% create map
% map struct
if ~isempty(sMap),
sMap = som_set(sMap,'topol',sTopol);
else
if ~prod(sTopol.msize),
if isnan(munits),
sTopol = som_topol_struct('data',D,sTopol);
else
sTopol = som_topol_struct('data',D,'munits',munits,sTopol);
end
end
sMap = som_map_struct(dim, sTopol);
end
if struct_mode,
sMap = som_set(sMap,'comp_names',comp_names,'comp_norm',comp_norm);
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% initialization
% train struct
sTrain = som_train_struct('algorithm','randinit');
sTrain = som_set(sTrain,'data_name',data_name);
munits = prod(sMap.topol.msize);
sMap.codebook = rand([munits dim]);
% set interval of each component to correct value
for i = 1:dim,
inds = find(~isnan(D(:,i)) & ~isinf(D(:,i)));
if isempty(inds), mi = 0; ma = 1;
else ma = max(D(inds,i)); mi = min(D(inds,i));
end
sMap.codebook(:,i) = (ma - mi) * sMap.codebook(:,i) + mi;
end
% training struct
sTrain = som_set(sTrain,'time',datestr(now,0));
sMap.trainhist = sTrain;
return;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%