pandas 객체에서 타입별로 컬럼을 추출해서 처리하는 코드가 마음에 들어서 가져옴
numeric_cols = [cname for cname in X_train_full.columns if X_train_full[cname].dtype in ['int64', 'float64']]
low_cardinality_cols = [cname for cname in X_train_full.columns if X_train_full[cname].nunique() < 10 and
X_train_full[cname].dtype == "object"]
my_cols = low_cardinality_cols + numeric_cols
X_train = X_train_full[my_cols].copy()