在pandas中，如果一列是分类的，如何规范化数据范围？

df['column_name'] = df['column_name'].astype('category')

df['column_name'] = df['column_name'].cat.codes

from sklearn.preprocessing import MinMaxScaler

scaler = MinMaxScaler()
df['column_name'] = scaler.fit_transform(df['column_name'].values.reshape(-1, 1))

from sklearn.preprocessing import StandardScaler

scaler = StandardScaler()
df['column_name'] = scaler.fit_transform(df['column_name'].values.reshape(-1, 1))