comparison toolboxes/FullBNT-1.0.7/KPMtools/plotROCkpm.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [falseAlarmRate, detectionRate, area, th] = plotROC(confidence, testClass, col, varargin)
+% You pass the scores and the classes, and the function returns the false
+% alarm rate and the detection rate for different points across the ROC.
+%
+% [faR, dR] = plotROC(score, class)
+%
+%  faR (false alarm rate) is uniformly sampled from 0 to 1
+%  dR (detection rate) is computed using the scores.
+%
+% class = 0 => target absent
+% class = 1 => target present
+%
+% score is the output of the detector, or any other measure of detection.
+% There is no plot unless you add a third parameter that is the color of
+% the graph. For instance:
+% [faR, dR] = plotROC(score, class, 'r')
+%
+% faR, dR are size 1x1250
+
+if nargin < 3, col = []; end
+[scale01] = process_options(varargin, 'scale01', 1);
+
+S = rand('state');
+rand('state',0);
+confidence = confidence + rand(size(confidence))*10^(-10);
+rand('state',S)
+
+ndxAbs = find(testClass==0); % absent
+ndxPres = find(testClass==1); % present
+
+[th, j] = sort(confidence(ndxAbs));
+th = th(fix(linspace(1, length(th), 1250))); 
+
+cAbs = confidence(ndxAbs);
+cPres = confidence(ndxPres);
+for t=1:length(th)
+  if length(ndxPres) == 0
+    detectionRate(t) = 0;
+  else
+    detectionRate(t)  = sum(cPres>=th(t)) / length(ndxPres);
+  end
+  if length(ndxAbs) == 0
+    falseAlarmRate(t) = 0;
+  else
+    falseAlarmRate(t) = sum(cAbs>=th(t)) / length(ndxAbs);
+  end
+  
+  %detectionRate(t)  = sum(confidence(ndxPres)>=th(t)) / length(ndxPres);
+  %falseAlarmRate(t) = sum(confidence(ndxAbs)>=th(t)) / length(ndxAbs);
+  %detections(t)     = sum(confidence(ndxPres)>=th(t));
+  %falseAlarms(t)    = sum(confidence(ndxAbs)>=th(t));
+end
+
+area = sum(abs(falseAlarmRate(2:end) - falseAlarmRate(1:end-1)) .* detectionRate(2:end));
+
+if ~isempty(col)
+    h=plot(falseAlarmRate, detectionRate, [col '-']);
+    %set(h, 'linewidth', 2);
+    e = 0.05;
+    if scale01
+      axis([0-e 1+e 0-e 1+e])
+    else
+      % zoom in on the top left corner
+      axis([0-e 0.5+e 0.5-e 1+e])
+    end
+    grid on
+    ylabel('detection rate')
+    xlabel('false alarm rate')
+end