关于‘df’ is not defined,这个要怎么解决

df=(df-df.min())/(df.max()-df.min())
train_data=df.sample(frac=0.8,replace=False)
test_data=df.drop(train_data.index)
x_train=train_data['area'].values.reshape(-1, 1)
y_train=train_data['price'].values
x_test=test_data['area'].values.reshape(-1, 1)
y_test=test_data['price'].values
from sklearn.linear_model import SGDRegressor
import joblib
model=SGDRegressor(max_iter=500,learning_rate='constant',eta0=0.01)
model.fit(x_train,y_train)
pre_score=model.score(x_train,y_train)
print('score=',pre_score)
print('coef=',model.coef_,'intercept=',model.intercept_)

数据还没导入呢，要df = pd.read_csv("")
如有用请采纳