Scikit Learn Pipeline

from sklearn.pipeline import Pipeline
from sklearn.preprocessing import RobustScaler
from sklearn.compose import ColumnTransformer
from sklearn.impute import SimpleImputer 


pipeline_steps = [
    ('mean_imputer', SimpleImputer(strategy='mean')),
    ('scaler', RobustScaler())
]

preprocess_pipeline = Pipeline(pipeline_steps)

X_train = preprocess_pipeline.fit_transform(df)
X_test = preprocess_pipeline.fit_transform(df_test)