基于sklearn快速实现11种机器学习回归模型的训练与评估
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作者：小白熊
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一、概述
在当今数据科学的领域中，选择合适的机器学习模型是推动任务决策的重要一步。随着数据规模的快速扩张，机器学习模型不仅在学术研究中发挥着至关重要的作用，而且在金融、医疗、电子商务、制造业等各行各业的实际应用中，已经成为解决复杂问题的核心工具。每个领域都积累了大量数据，并且这些数据量仍在不断增长，如何利用这些数据获得有价值的见解，驱动智能决策，是现代企业和研究机构面临的共同挑战。
然而，面对当前广泛的机器学习模型选择，需要在有限的时间内，快速、高效地搭建合适的模型并对其进行准确的评估。因此，scikit-learn 库凭借其丰富的功能和便捷的接口，成为了构建机器学习模型的首选工具之一。
本文旨在介绍如何使用 scikit-learn 实现 11 种流行的机器学习回归模型，读者将学习如何从数据准备阶段入手，依次进行模型的构建、训练和优化，最终完成模型的性能评估。本文将通过简洁明了的代码示例，帮助读者快速掌握每个回归模型的使用方法，并深入理解每种模型的特点、优缺点及其适用场景。
二、数据准备
首先需要准备一个数据集。这里使用加州房价数据集作为示例，并使用`train_test_split`函数按照8：2的比例划分训练集和验证集。
import pandas as pd
from sklearn.datasets import fetch_california_housing
from sklearn.model_selection import train_test_split
# 加载数据集
california = fetch_california_housing()
X = california.data
y = california.target
# 划分训练集和验证集
X_train, X_val, y_train, y_val = train_test_split(X, y, test_size=0.2, random_state=42)
三、11种机器学习回归模型
1. 线性回归 (Linear Regression)
from sklearn.linear_model import LinearRegression
from sklearn.metrics import mean_squared_error, mean_absolute_error, r2_score
import numpy as np
# 初始化模型
lr_model = LinearRegression()
# 训练模型
lr_model.fit(X_train, y_train)
# 预测
y_train_pred = lr_model.predict(X_train)
y_val_pred = lr_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Linear Regression:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
2. 岭回归 (Ridge Regression)
from sklearn.linear_model import Ridge
# 初始化模型
ridge_model = Ridge()
# 训练模型
ridge_model.fit(X_train, y_train)
# 预测
y_train_pred = ridge_model.predict(X_train)
y_val_pred = ridge_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Ridge Regression:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
3. Lasso 回归 (Lasso Regression)
from sklearn.linear_model import Lasso
# 初始化模型
lasso_model = Lasso()
# 训练模型
lasso_model.fit(X_train, y_train)
# 预测
y_train_pred = lasso_model.predict(X_train)
y_val_pred = lasso_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Lasso Regression:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
4. 决策树回归 (Decision Tree Regressor)
from sklearn.tree import DecisionTreeRegressor
# 初始化模型
dt_model = DecisionTreeRegressor()
# 训练模型
dt_model.fit(X_train, y_train)
# 预测
y_train_pred = dt_model.predict(X_train)
y_val_pred = dt_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Decision Tree Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
5. 随机森林回归 (Random Forest Regressor)
from sklearn.ensemble import RandomForestRegressor
# 初始化模型
rf_model = RandomForestRegressor(n_estimators=100, random_state=42)
# 训练模型
rf_model.fit(X_train, y_train)
# 预测
y_train_pred = rf_model.predict(X_train)
y_val_pred = rf_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Random Forest Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
6. 支持向量回归 (Support Vector Regression)
from sklearn.svm import SVR
# 初始化模型
svr_model = SVR()
# 训练模型
svr_model.fit(X_train, y_train)
# 预测
y_train_pred = svr_model.predict(X_train)
y_val_pred = svr_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Support Vector Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
7. K 近邻回归 (K-Neighbors Regressor)
from sklearn.neighbors import KNeighborsRegressor
# 初始化模型
knn_model = KNeighborsRegressor()
# 训练模型
knn_model.fit(X_train, y_train)
# 预测
y_train_pred = knn_model.predict(X_train)
y_val_pred = knn_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'K-Neighbors Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
8. AdaBoost 回归 (AdaBoost Regressor)
from sklearn.ensemble import AdaBoostRegressor
from sklearn.tree import DecisionTreeRegressor
# 初始化模型
ada_model = AdaBoostRegressor(base_estimator=DecisionTreeRegressor(), n_estimators=50, random_state=42)
# 训练模型
ada_model.fit(X_train, y_train)
# 预测
y_train_pred = ada_model.predict(X_train)
y_val_pred = ada_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'AdaBoost Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
9. 梯度提升回归 (Gradient Boosting Regressor)
from sklearn.ensemble import GradientBoostingRegressor
# 初始化模型
gb_model = GradientBoostingRegressor(n_estimators=100, random_state=42)
# 训练模型
gb_model.fit(X_train, y_train)
# 预测
y_train_pred = gb_model.predict(X_train)
y_val_pred = gb_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'Gradient Boosting Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
10. XGBoost 回归 (XGBoost Regressor)
import xgboost as xgb
# 初始化模型
xgb_model = xgb.XGBRegressor(n_estimators=100, random_state=42)
# 训练模型
xgb_model.fit(X_train, y_train)
# 预测
y_train_pred = xgb_model.predict(X_train)
y_val_pred = xgb_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'XGBoost Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
11. LightGBM 回归 (LightGBM Regressor)
import lightgbm as lgb
# 初始化模型
lgb_model = lgb.LGBMRegressor(n_estimators=100, random_state=42)
# 训练模型
lgb_model.fit(X_train, y_train)
# 预测
y_train_pred = lgb_model.predict(X_train)
y_val_pred = lgb_model.predict(X_val)
# 计算指标
mse_train = mean_squared_error(y_train, y_train_pred)
mae_train = mean_absolute_error(y_train, y_train_pred)
rmse_train = np.sqrt(mse_train)
r2_train = r2_score(y_train, y_train_pred)
mse_val = mean_squared_error(y_val, y_val_pred)
mae_val = mean_absolute_error(y_val, y_val_pred)
rmse_val = np.sqrt(mse_val)
r2_val = r2_score(y_val, y_val_pred)
# 打印指标
print(f'LightGBM Regressor:')
print(f"训练集 MSE: {mse_train:.2f}, MAE: {mae_train:.2f}, RMSE: {rmse_train:.2f}, R²: {r2_train:.2f}")
print(f"验证集 MSE: {mse_val:.2f}, MAE: {mae_val:.2f}, RMSE: {rmse_val:.2f}, R²: {r2_val:.2f}")
print("*" * 100)
四、结束语
在本文中，我们实现了 11 种流行的回归模型，并使用均方误差 (MSE)、平均绝对误差 (MAE)、均方根误差 (RMSE) 和决定系数 (R²) 对模型进行了评估。根据评估结果，我们可以选择最适合我们任务的回归模型。你可以根据实际需求调整模型的参数，进一步提升模型性能。
希望这篇文章能帮助你更好地理解和运用 scikit-learn 进行机器学习回归任务！