simpleroc.m

来自「data description toolbox 1.6 单类分类器工具包」· M 代码 · 共 79 行

function [f,thr] = simpleroc(netout,truelab)
%SIMPLEROC Basic receiver-operating characteristic curve
%
%      F = SIMPLEROC(NETOUT,TRUELAB)
%
% Compute the ROC curve for the network output NETOUT, given the true
% labels TRUELAB. TRUELAB should contain 0-1 values, where 0 is the
% correct output if (netout < some_threshold) and 1 when the
% (netout > some_threshold). Output F contains [FNr FPr].
%
% This version returns a vector of the same length as NETOUT and
% TRUELAB. Maybe this will be shortened/subsampled in the future.
%
% See also: dd_roc, plotroc

% Copyright: D.M.J. Tax, [e-mail]
% Faculty EWI, Delft University of Technology
% P.O. Box 5031, 2600 GA Delft, The Netherlands


% Check the size of the netout vector:
if size(netout,2)~=1
	netout = netout';
	if size(netout,1)~=1
		error('Please make netout a column vector');
	end
end

% So all sizes become:
n = size(netout,1);
n_t = sum(truelab);
n_o = n - n_t;

% Sort the network output:
[sout,I] = sort(netout);
% and reorder the true-labels accordingly:
slab = truelab(I);

% Make the index arrays for the target and outlier objects:
slabt = slab;
slabo = slab-1;

% Check if there are identical outputs, and ...
[uout,dummy,J] = unique(sout);
% Change the slab such that the identical values are on top of each other
if size(uout,1)<n
	%warning('dd_tools:NoUniqueROC',...
	%	'There are identical values in NETOUT, the ROC is not uniquely defined.');
	n = max(J);
	slabt2 = zeros(n,1);
	slabo2 = zeros(n,1);
	for j=1:n  % count how many of each of the values occur, and store
		% the approprate number in slabt2 and slabo2:
		Jj = find(J==j);
		slabt2(j) = sum(slabt(Jj));
		slabo2(j) = sum(slabo(Jj));
	end
	slabt = slabt2;
	slabo = slabo2;
end

% Faster version:
	% number of 1's left from thresh.
	% number of 0's right from thresh.
f = [cumsum(slabt) (n_o+cumsum(slabo))];
% fix the beginning of the curve to (0,n_o)
f = [0 n_o; f];

% ... and normalize:
f = f./repmat([n_t n_o],n+1,1);

% On request, also the thresholds are returned:
if nargout>1
	thr = uout;
end

return