How to find the ROC curve?

*Hello ,

I want to find the ROC curve in MATLAB. I have used a linear classification first using classify command and then I need to plot the ROC.*

I used this code:*

%%%%

clc close all

clear all

%% MY FEATURES

features = xlsread('ExtractedFeatures.xls');

numFeatures = 418;

%% Define ground truth

groundTruthGroup = cell(numFeatures,1); groundTruthGroup(1:351) = cellstr('normal'); groundTruthGroup(352:end) = cellstr('abnormal');

%% Select features

featureSelcted = [features(:,1),features(:,2)];

%% Run LDA

[ldaClass, ldaResubErr] = classify(featureSelcted(:,1), featureSelcted(:,2), groundTruthGroup, 'linear');

bad = ~strcmp(ldaClass,groundTruthGroup);

ldaResubErr2 = sum(bad)/numFeatures;

[ldaResubCM,grpOrder] = confusionmat(groundTruthGroup,ldaClass);

%% ROC curve

[X,Y,T,AUC] = perfcurve(featureSelcted(:,1),ldaResubErr,'normal');

plot(X,Y)

xlabel('False positive rate'); ylabel('True positive rate')

title('ROC for classification by lheogistic regression')

%%%%%%

*However, I'm having an error:

Error using perfcurve>membership (line 633) Positive class is not found in the input data.

Error in perfcurve (line 387) [W,subYnames] = membership(labels(sorted),weights(sorted),...

Error in Untitled33 (line 23) [X,Y,T,AUC] = perfcurve(featureSelcted(:,1),featureSelcted(:,2),'normal');

Can any one help me in plotting the ROC curve?

I already attached the Excel sheet.

Many thanks in advance !*

[Image Analyst]

You forgot to post the error. You just snipped out a very small portion of it. Please post the ENTIRE error. ALL the red text , with line numbers, code statements, everything. Also, below in the Products section please list what toolboxes you used, for example what toolbox perfcurve and confusionmat are in. I don't think I have those so I won't be able to help you.