I am using ROC Curve nodes on my server to create interactive views (KNIME version is 4.7.1).
Sometimes when I run that workflow, the ROC Curve doesn’t work - it doesn’t get a red light, it gets stuck at a yellow light. The error message is “reason unknown” and we don’t know why.
I have experienced this same problem before and in my case, the problem arised when there was only one predicted class instead of two. The -ROC Curve- node does not like this special case but instead of failing, it remains in yellow state.
The solution in this case is to check before using the -ROC Curve- node, whether your model predicted samples for the two classes and only if this is the case, generate a curve ROC. Otherwise the -ROC Curve- node should be bypassed using for instance the -Case Switch Start- and a --Case Switch End- nodes :