# 파티셔닝하기
>>> X = df_adv.loc[:, ['TV']]
>>> Y = df_adv['sales']
>>> print(X.shape)
(200, 1)
>>> X_train, X_test, Y_train, Y_test = model_selection.train_test_split(X, Y, test_size=0.3, random_state=42)

>>> regr = linear_model.LinearRegression()
>>> regr.fit(X_train, Y_train)
>>> regr.score(X_train, Y_train)   # R^2
0.5736021199591975

>>> regr.coef_
array([0.0464078])

>>> Y_pred = regr.predict(X_test)
>>> np.mean((Y_pred - Y_test) ** 2)   # MSE
8.970991242413616

>>> plt.scatter(X_test, Y_test, color='black')
>>> plt.plot(X_test, Y_pred, color='blue', linewidth=3)
>>> plt.xlabel("TV")
>>> plt.ylabel("sales")
>>> plt.show()