应用python随机森林回归模型训练好模型后，如何进行预测？为什么预测值会这么小，且出现多个相同的异常值？

Question

from sklearn.datasets import load_boston
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler
from sklearn.ensemble import RandomForestRegressor, ExtraTreesRegressor, GradientBoostingRegressor
from sklearn.metrics import r2_score, mean_squared_error, mean_absolute_error
import numpy as np


#随机森林回归


# 1 准备数据
# 读取波士顿地区房价信息
boston = load_boston()
#print("boston:", boston)
# 查看数据描述
# print(boston.DESCR)   # 共506条波士顿地区房价信息，每条13项数值特征描述和目标房价
# 查看数据的差异情况
# print("最大房价：", np.max(boston.target))   # 50
# print("最小房价：",np.min(boston.target))    # 5
# print("平均房价：", np.mean(boston.target))   # 22.532806324110677

x = boston.data
y = boston.target
print("x.shape:", x.shape)
print("y.shape:", y.shape)
# 2 分割训练数据和测试数据
# 随机采样25%作为测试 75%作为训练
x_train, x_test, y_train, y_test = train_test_split(x, y, test_size=0.25, random_state=33)
print("x_train.shape:", x_train.shape)
print("x_test.shape:", x_test.shape)
print("y_train.shape:", y_train.shape)
print("y_test.shape:", y_test.shape)
# 3 训练数据和测试数据进行标准化处理
ss_x = StandardScaler()
x_train = ss_x.fit_transform(x_train)
x_test = ss_x.transform(x_test)

ss_y = StandardScaler()
y_train = ss_y.fit_transform(y_train.reshape(-1, 1))
y_test = ss_y.transform(y_test.reshape(-1, 1))


# 随机森林回归
rfr = RandomForestRegressor()
# 训练
rfr.fit(x_train, y_train)
# 预测 保存预测结果
rfr_y_predict = rfr.predict(x_test)
#对所有特征数据进行预测
Y_predict=rfr.predict(x)


# 随机森林回归模型评估
print("随机森林回归的默认评估值为：", rfr.score(x_test, y_test))
print("随机森林回归的R_squared值为：", r2_score(y_test, rfr_y_predict))
print("随机森林回归的均方误差为:", mean_squared_error(ss_y.inverse_transform(y_test),
                                          ss_y.inverse_transform(rfr_y_predict)))
print("随机森林回归的平均绝对误差为:", mean_absolute_error(ss_y.inverse_transform(y_test),
                                             ss_y.inverse_transform(rfr_y_predict)))
print(y)
print(Y_predict)

#输出的结果
x.shape: (506, 13)
y.shape: (506,)
x_train.shape: (379, 13)
x_test.shape: (127, 13)
y_train.shape: (379,)
y_test.shape: (127,)
随机森林回归的默认评估值为： 0.8469322253577488
随机森林回归的R_squared值为： 0.8469322253577488
随机森林回归的均方误差为: 11.869073401574813
随机森林回归的平均绝对误差为: 2.229212598425197
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 1.17246098 1.17246098]

Answer 1

随机森林也是要调参数的，不是拿来就直接用的。