Multilabel-indicator is not supported for confusion matrix

Question

multilabel-indicator is not supported is the error message I get, when trying to run:

confusion_matrix(y_test, predictions)

y

Answer 1

from sklearn.metrics import confusion_matrix

predictions_one_hot = model.predict(test_data)
cm = confusion_matrix(labels_one_hot.argmax(axis=1), predictions_one_hot.argmax(axis=1))
print(cm)

Output would be something like this:

[[298   2  47  15  77   3  49]
 [ 14  31   2   0   5   1   2]
 [ 64   5 262  22  94  38  43]
 [ 16   1  20 779  15  14  34]
 [ 49   0  71  33 316   7 118]
 [ 14   0  42  23   5 323   9]
 [ 20   1  27  32  97  13 436]]

Answer 2

The confusion matrix takes a vector of labels (not the one-hot encoding). You should run

confusion_matrix(y_test.values.argmax(axis=1), predictions.argmax(axis=1))

Answer 3

No, your input to confusion_matrix must be a list of predictions, not OHEs (one hot encodings). Call argmax on your y_test and y_pred, and you should get what you expect.

confusion_matrix(
    y_test.values.argmax(axis=1), predictions.argmax(axis=1))

array([[1, 0],
       [0, 2]])