roc_auc_score - Only one class present in y_true

Question

I am doing a k-fold XV on an existing dataframe, and I need to get the AUC score. The problem is - sometimes the test data only contains 0s, and not 1s!

I tried usin

Answer 1

Simply modify the code with 0 to 1 make it work

import numpy as np
from sklearn.metrics import roc_auc_score
y_true = np.array([0, 1, 0, 0])
y_scores = np.array([1, 0, 0, 0])
roc_auc_score(y_true, y_scores)

I believe the error message has suggested that only one class in y_true (all zero), you need to give 2 classes in y_true.