function e = dd_F1(x,w)%DD_F1 compute the F1 score %%   E = DD_F1(X,W)%   E = DD_F1(X*W)%   E = X*W*DD_F1%% Compute the F1 score of a dataset, defined as:%           2*precision*recall%     F1 =  ------------------%           precision + recall%% See also: dd_error, dd_roc% Copyright: D.M.J. Tax, D.M.J.Tax@prtools.org% Faculty EWI, Delft University of Technology% P.O. Box 5031, 2600 GA Delft, The Netherlands% Do it the same as testc:% When no input arguments are given, we just return an empty mapping:if nargin==0		e = mapping(mfilename,'fixed');	returnelseif nargin == 1	% Now we are doing the actual work, our input is a mapped dataset:	% get the precision and recall:	[dummy,f] = dd_error(x);	% do some checks:	if ~isfinite(f(1))		warning('dd_tools:NonfiniteOutputs',...			'The precision is not finite (all data is classified outlier)');		e = nan;		return;	end	if ~isfinite(f(2))		warning('dd_tools:NonfiniteOutputs',...			'The recall is not finite (no target data present?)');		e = nan;		return	end	% and compute F1:	e = (2*f(1)*f(2))/(f(1)+f(2));else	ismapping(w);	istrained(w);	e = feval(mfilename,x*w);endreturn