Process categorical and numerical variables separately

import numpy as np
 
from sklearn.compose import ColumnTransformer
from sklearn.pipeline import Pipeline
from sklearn.impute import SimpleImputer
from sklearn.preprocessing import OrdinalEncoder
 
num_pipeline = Pipeline(steps=[
    ('imputer', SimpleImputer(strategy='constant', fill_value=-np.inf))
])
 
cat_pipeline = Pipeline(steps=[
    ('imputer', SimpleImputer(strategy='constant', fill_value='missing')),
    ('encoder', OrdinalEncoder())
])
 
preprocessor = ColumnTransformer(
    transformers=[
        ('num', num_pipeline, numerical_cols),
        ('cat', cat_pipeline, categorical_cols)
    ]
)