Sklearn "pipeline Instance Is Not Fitted Yet." Error, Even Though It Is

A similar question is already asked, but the answer did not help me solve my problem: Sklearn components in pipeline is not fitted even if the whole pipeline is? I'm trying to use

Solution 1:

You cannot use the export_text function on the whole pipeline as it only accepts Decision Tree objects, i.e. DecisionTreeClassifier or DecisionTreeRegressor. Only pass the fitted estimator of your pipeline and it will work:

text_representation = tree.export_text(classifier['classifier'])

The error message stating that the Pipeline object is not fitted is due to the check_is_fitted function of scikit-learn. It works by checking the presence of fitted attributes (ending with a trailing underscore) on the estimator. Since Pipeline objects do not expose such attributes, the check fails and raises the error, although it is indeed fitted. But that is not a problem since Pipeline objects are not meant to be used that way anyway.