list all categorical features transforms in sklearn.preprocessing code example

Example 1: feature scaling in python

from sklearn.preprocessing import MinMaxScaler
scaler = MinMaxScaler()
from sklearn.linear_model import Ridge
X_train, X_test, y_train, y_test = train_test_split(X_data, y_data,
                                                   random_state = 0)

X_train_scaled = scaler.fit_transform(X_train)
X_test_scaled = scaler.transform(X_test)

Example 2: Scaling features to a range

# Scaling features to a range using MaxAbsScaler

X_train = np.array([[ 1., -1.,  2.],
                    [ 2.,  0.,  0.],
                    [ 0.,  1., -1.]])

max_abs_scaler = preprocessing.MaxAbsScaler()
X_train_maxabs = max_abs_scaler.fit_transform(X_train)
X_train_maxabs
# array([[ 0.5, -1.,  1. ],
#        [ 1. ,  0. ,  0. ],
#        [ 0. ,  1. , -0.5]])
X_test = np.array([[ -3., -1.,  4.]])
X_test_maxabs = max_abs_scaler.transform(X_test)
X_test_maxabs
# array([[-1.5, -1. ,  2. ]])
max_abs_scaler.scale_
# array([2.,  1.,  2.])