# How to plot Receiver Operating Characteristics Curve (ROC)?

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Sameema Tariq on 7 May 2020
Commented: Sameema Tariq on 7 May 2020
I have to calculate the ROC which is a graph between TPR and FPR. TPR and FPR are calculated from this LINK. But I am not understanding how do I plot ROC with it. As ROC is dependent upon the threshold values to plot between TPR and FPR. But FPR and TPR taken from this link are independent of threshold values. Kindly guide me what should I do to plot ROC?

KALYAN ACHARJYA on 7 May 2020
Edited: KALYAN ACHARJYA on 7 May 2020
The answered, which I have provided (manual process for non supervised classification algorithm), when I was very beginnner on MATLAB. There are other smart ways to do the same by buidling confusion matrix. Get the individually ROC points for same threshold values for multiple images. please refer the TOM paper to get the understanding of ROC analysis
I have provided another answer (on ROC), please check, it may be OK.
Sameema Tariq on 7 May 2020
Thanks this link is very helpful. Please guide me more on this. I am confused on determining the threshold value that how will it effect the TPR(sensitivity) and FPR(1-specificity)? I have calculated TPR and FPR as this:
TPR = TP/(TP+FN+eps);
FPR = FP/(FP+TN+eps);
And in this there is no threshold that is effecting it. And I am calculating TPs and FPs from this LINK. And also there is no threshold that is effecting TPs and FPs. Kindly guide me. It will be a great favor. Thanks in Advance

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