function?auc?=?plotroc（yxparams）
%plotroc?draws?the?recevier?operating?characteristic（ROC）?curve.
%
%auc?=?plotroc（training_label?training_instance?[?libsvm_options?-v?cv_fold]）?
%??Use?cross-validation?on?training?data?to?get?decision?values?and?plot?ROC?curve.
%
%auc?=?plotroc（testing_label?testing_instance?model）?
%??Use?the?given?model?to?predict?testing?data?and?obtain?decision?values
%??for?ROC
%
%?Example:
%???
%?	load（‘heart_scale.mat‘）;?
%?	plotroc（heart_scale_label?heart_scale_inst‘-v?5‘）;
%
%	[yx]?=?libsvmread（‘heart_scale‘）;
%???	model?=?svmtrain（yx）;
%?	plotroc（yxmodel）;
	rand（‘state‘0）;?%?reset?random?seed
	if?nargin?		help?plotroc
		return
	elseif?isempty（y）?|?isempty（x）
		error（‘Input?data?is?empty‘）;
	elseif?sum（y?==?1）?+?sum（y?==?-1）?~=?length（y）
		error（‘ROC?is?only?applicable?to?binary?classes?with?labels?1?-1‘）;?%?check?the?trainig_file?is?binary
	elseif?exist（‘params‘）?&&?~ischar（params）
		model?=?params;
		[predict_labelmsedeci]?=?svmpredict（yxmodel）;?%?the?procedure?for?predicting
		auc?=?roc_curve（deci*model.Label（1）y）;
	else
		if?~exist（‘params‘）
			params?=?[];
		end
		[paramfold]?=?proc_argv（params）;?%?specify?each?parameter
		if?fold?<=?1
			error（‘The?number?of?folds?must?be?greater?than?1‘）;
		else	
			[decilabel_y]?=?get_cv_deci（yxparamfold）;?%?get?the?value?of?decision?and?label?after?cross-calidation
			auc?=?roc_curve（decilabel_y）;?%?plot?ROC?curve
		end
	end
end

function?[resufold]?=?proc_argv（params）
	resu=params;
	fold=5;
	if?~isempty（params）?&&?~isempty（regexp（params‘-v‘））
????????[fold_valfold_startfold_end]?=?regexp（params‘-v\s+\d+‘‘match‘‘start‘‘end‘）;
????????if?~isempty（fold_val）
????????????[temp1fold]?=?strread（[fold_val{:}]‘%s?%u‘）;
????????????resu（[fold_start:fold_end]）?=?[];
????????else
????????????error（‘Number?of?CV?folds?must?be?specified?by?“-v?cv_fold“‘）;
????????end
????end
end

function?[decilabel_y]?=?get_cv_deci（prob_yprob_xparamnr_fold）
	l=length（prob_y）;
	deci?=?ones（l1）;
	label_y?=?ones（l1）;	?
	rand_ind?=?randperm（l）;?
	for?i=1:nr_fold?%?Cross?training?:?folding
		test_ind=rand_ind（[floor（（i-1）*l/nr_fold）+1:floor（i*l/nr_fold）]‘）;
		train_ind?=?[1:l]‘;
		train_ind（test_ind）?=?[];
		model?=?svmtrain（prob_y（train_ind）prob_x（train_ind:）param）;	???
		[predict_labelmsesubdeci]?=?svmpredict（prob_y（test_ind）prob_x（test_ind:）model）;
		deci（test_ind）?=?subdeci.*model.Label（1）;
		label_y（test_ind）?=?prob_y（test_ind）;
	end
end

function?auc?=?roc_curve（decilabel_y）
	[valind]?=?sort（deci‘descend‘）;
	roc_y?=?label_y（ind）;
	stack_x?=?cumsum（roc_y?==?-1）/sum（roc_y?==?-1）;
	stack_y?=?cumsum（roc_y?==?1）/sum（roc_y?==?1）;
???
	auc?=?sum（（stack_x（2:length（roc_y）1）-stack_x（1:length（roc_y）-11））.*stack_y（2:length（roc_y）1））

????????%Comment?the?above?lines?if?using?perfcurve?of?statistics?toolbox
????????%[stack_xstack_ythreauc]=perfcurve（label_ydeci1）;
?????????len=length（stack_x）;
?????????l=1;
?????????for?i=1:10:len
?????????stack_x1（l）=?st

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????3217??2013-06-01?16:30??plotroc.m

-----------?---------??----------?-----??----

?????????????????3217????????????????????1