sklearn 使用joblib保存模型，并解决cannot import name joblib from sklearn.externals报错

cannot import name joblib from sklearn.externals的原因是使用joblib不需要从sklearn中导入了，解决方法：

import joblib
model = DecisionTreeRegressor(max_features=None,max_depth='sqrt')
joblib.dump(model, "train_model.m") # 保存

# model = joblib.load('train_model.m') # 读取