How to calculate true positive, true negative, false positive and false negative?

Hello everyone!

I created artificial neural network to compute answers for my diagnosis. Now, I would like to compare the amount of true positive, true negative, false positive and false negative. I was thinking about creating a loop and count every values.

Thank you for your help.

Answer 1

[Shreeya]

To calculate the TP, TN, FP, FN, you can refer to the code down below.

% An example considering 1 & 2 as positive and 3 as negative:

real = [1	1	1	1	1	2	2	2	2	2	2	2	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3];
predicted = [2	2	3	2	1	2	3	2	3	3	3	3	3	3	3	3	3	3	3	3	2	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3	3];

realPos = (real==1) | (real == 2);
realNeg = ~realPos;
predictedPos = (predicted==1) | (predicted == 2);
predictedNeg = ~predictedPos;

TP = sum(predictedPos & realPos)  % 6
FP = sum(predictedPos & realNeg)  % 1
TN = sum(predictedNeg & realNeg)  % 27
FN = sum(predictedNeg & realPos)  % 6

This code has been sourced from the MATLAB answer linked here: https://www.mathworks.com/matlabcentral/answers/1997058-how-can-i-calculate-true-positive-false-positive-true-negative-and-false-negative-of-real-and-pred

You can refer to the discussion for more details.