Specificity in scikit learn

Question

I need specificity for my classification which is defined as : TN/(TN+FP)

I am writing a custom scorer function :

from sklearn.         


        

Answer 1

You could get specificity from the confusion matrix. For a binary classification problem, it would be something like:

from sklearn.metrics import confusion_matrix
y_true = [0, 0, 0, 1, 1, 1, 1, 1]
y_pred = [0, 1, 0, 1, 0, 1, 0, 1]
tn, fp, fn, tp = confusion_matrix(y_true, y_pred).ravel()
specificity = tn / (tn+fp)