function [X, Class] = cvLibsvmRead(filename)
% cvLibsvmRead - Read a LIBSVM format file and returns matlab matrix data
%
% Synopsis
% [X, Class] = cvLibsvmRead(filename)
%
% Description
% cvLibsvmRead reads a LIBSVM [1] data format file and returns
% a matlab matrix data.
% The format of training and testing data file in LIBSVM is as:
% <label> <index1>:<value1> <index2>:<value2> ...
% ...
% ...
%
% Inputs ([]s are optional)
% (string) filename The filename to be read
%
% Outputs ([]s are optional)
% (matrix) X D x N matrix representing feature vectors by columns
% where D is the number of dimensions and N is the
% number of vectors.
% (vector) Class 1 x N vector representing class labels
%
% See also
% cvLibsvmWrite
% References
% [1] Chih-Chung Chang and Chih-Jen Lin, LIBSVM: a library for support
% vector machines, 2001, http://www.csie.ntu.edu.tw/~cjlin/libsvm
%
% Authors
% Naotoshi Seo <sonots(at)sonots.com>
%
% License
% The program is free to use for non-commercial academic purposes,
% but for course works, you must understand what is going inside to use.
% The program can be used, modified, or re-distributed for any purposes
% if you or one of your group understand codes (the one must come to
% court if court cases occur.) Please contact the authors if you are
% interested in using the program without meeting the above conditions.
%
% Changes
% 12/01/2007 First Edition
fid = fopen(filename, 'r');
X = []; Class = [];
for n=1:Inf
tline = fgetl(fid);
if ~ischar(tline), break, end
[class,remain]=strtok(tline,' ');
Class(n) = str2num(class);
while ~strcmp(remain,'')
[d,remain]=strtok(remain,':');
[num,remain]=strtok(remain(2:end),' ');
X(str2num(d),n) = str2num(num);
end
end
% format = ['%g ', repmat('%g:%g ', 1, D)];
% X = fscanf(fid, format, [2*D+1, Inf]);
% Class = X(1,:);
% X = X(3:2:end,:);
fclose(fid);
end
