dataprocessing

 Column Transformer

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from sklearn.compose import ColumnTransformer

ct = ColumnTransformer(

    transformers=[

        ("ohe", OneHotEncoder(sparse_output=False), ["city", "gender"])

    ], 

    remainder="passthrough" # Keeps all other columns (like age, salary)

).set_output(transform="pandas")

df_processed = ct.fit_transform(df)

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scaler = StandardScaler().set_output(transform="pandas")
df_scaled = scaler.fit_transform(df)