sklearn.exceptions.NotFittedErro

报错：sklearn.exceptions.NotFittedError: This StandardScaler instance is not fitted yet. Call 'fit' with a
原因：
sklearn.exceptions.notfitte错误：尚未安装此StandardScaler实例。称“fit”
解决方法

ss_X = StandardScaler()  
ss_y = StandardScaler()
X_train = ss_X.fit_transform(X_train)            
X_test  = ss_X.transform(X_test)