An Estimator is a generalization of a machine learning algorithm. It consumes a DataFrame and produces a Transformer. Estimators can be executed using a Fit operation.

Estimator usage diagram Estimator usage diagram


A Logistic Regression is an operation that outputs an untrained model, which is an Estimator. It is passed to a Fit operation. We get a trained model as a result of fitting. The trained model is a Transformer that can be used in a Transform operation for scoring on new data.

estimator example