FunctionTransformer in Pipeline

function_transformer.py

from sklearn.preprocessing import FunctionTransformer

# The function we want to convert to a class for our pipeline
def transform_yes_no(X):
  X['international plan'] = X['international plan'].apply(lambda x: 1 if x.lower() == 'yes' else 0)
  X['voice mail plan'] = X['voice mail plan'].apply(lambda x: 1 if x.lower() == 'yes' else 0)
  return X

# Convert to class for pipeline
YesNoTransformer = FunctionTransformer(transform_yes_no)

# Define the pipeline
pipeline = Pipeline(steps= [
                    ("TransformCategorical", YesNoTransformer),
                    ("SMOTE", SMOTE()),
                    ("GradientBooster", GradientBoostingClassifier())
                    ])