Is there an easy way to obtain a confusion matrix?

[goerch]

I'm trying

    confusion_matrix(y_test, y_pred)

with sklearn's method, but am getting the error message

ValueError: You appear to be using a legacy multi-label data representation. Sequence of sequences are no longer supported; use a binary array or sparse matrix instead - the MultiLabelBinarizer transformer can convert to this format.

[soerenetler]

Hi @goerch, I assume your y_true and y_pred are nested lists, right? For the confusion matrix function you have to flatten them first. Does that help?
Have a great weekend,
Sören

[goerch]

Thanks @soerenetler, excellent advice. I didn't bother to read the source before, but now I have

from sklearn_crfsuite.utils import flatten

mcm = multilabel_confusion_matrix(flatten(y_test), flatten(y_pred))

which works as intended.