getdatafieldvalue.m.svn-base

a function inside machine learning

function val = getDataFieldValue(d, name, rowIndices, colIndices) 
%Get a field from a data struct 

% Copyright (C) 2006 Charanpal Dhanjal 

% This library is free software; you can redistribute it and/or
% modify it under the terms of the GNU Lesser General Public
% License as published by the Free Software Foundation; either
% version 2.1 of the License, or (at your option) any later version.
% 
% This library 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
% Lesser General Public License for more details.
% 
% You should have received a copy of the GNU Lesser General Public
% License along with this library; if not, write to the Free Software
% Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
% USA

if (nargin < 2)
    fprintf('%s\n', help(sprintf('%s', mfilename)));
    error('Incorrect number of inputs - see above usage instructions.');
end

if ~isa(d, 'data')
    error('First argument is not a data object'); 
end

if d.numExamples == 0 
    error('Using uninitialised data object'); 
end 

if ~isfield(d.exampleIndices, name)
    error('Field %s does not exist', name);
end

if nargin >= 3 & (sum(rowIndices > d.numExamples) | sum(rowIndices < 1))
    error('Example row indices are out of range. Must be between 1 and %d.', d.numExamples); 
end 

if nargin == 4 & (sum(colIndices > length(d.colIndices.(name))) | sum(colIndices < 1))
    error('Example column indices are out of range. Must be between 1 and %d.', length(d.colIndices.(name))); 
end 

if (nargin >= 3)
    dataRowIndices = d.exampleIndices.(name)(rowIndices);
else
    dataRowIndices = d.exampleIndices.(name);
end

if (nargin == 4)
    dataColIndices = d.colIndices.(name)(colIndices);
else
    dataColIndices = d.colIndices.(name);
end

global dataValues; 

val = dataValues{d.globalIndices.(name), 1}(dataRowIndices, dataColIndices);