function [ X,header, idxRem ] = pnParseData(X,header,idxRem)
%PNPARSEDATA	Remove bad data features
%	[ X,header ] = pnParseData(X,header) removes infinites, features which
%	are singular valued, and features which are all NaNs.
%
%	Inputs:
%		X		- Numeric matrix of data
%		header	- Cell array of strings
%
%	Outputs:
%		X		- Numeric matrix of data with bad features removed
%		header	- Cell array of strings with bad features removed
%
%
%	Example
%		bpath = './set-a/';
%		data = pnLoadTextFilesCell(bpath);
%		[X,header] = pnExtractData(data,'first');
%		[X,header] = pnParseData(X,header);
%	See also PNDEVELOPMODELS PNMAIN

%	References:
%		Physionet Challenge 2012

%	Copyright 2012 Alistair Johnson

%	$LastChangedBy: alistair $
%	$LastChangedDate: 2012-06-11 16:51:34 -0400 (Mon, 11 Jun 2012) $
%	$Revision: 60 $
%	Originally written on GLNXA64 by Alistair Johnson, 11-Jun-2012 09:13:57
%	Contact: alistairewj@gmail.com

X(isinf(X)) = NaN;
if nargin<3 % idxRem not provided
    idxRem = sum(isnan(X),1) > 0.99*size(X,1);
    
    %=== Delete singular valued features
    for m=1:size(X,2)
        Xuniq = unique(X(:,m));
        if numel(Xuniq)==1 || ( numel(Xuniq)==2 && any(isnan(Xuniq)) )
            idxRem(m) = true;
        end
    end
end

X(:,idxRem) = [];
header(:,idxRem) = [];
end