一. 线性回归
1. lm()函数返回的是对于输入变量的预测模型,返回的结果可以配合许多函数进行使用。
> lm.model <- lm(wt ~ mpg, data = mtcars)
> coefficients(lm.model) # 提取系数
(Intercept) mpg
6.047255 -0.140862
> confint(lm.model, level=0.95) # 得到线性模型相关系数的分布后,限定区间,得到边界点的值
2.5 % 97.5 %
(Intercept) 5.4168245 6.6776856
mpg -0.1709569 -0.1107671
> fitted(lm.model) # 用建立的模型去预测wt
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive Hornet Sportabout Valiant Duster 360
3.089154 3.089154 2.835602 3.032809 3.413136 3.497653 4.032929
Merc 240D Merc 230 Merc 280 Merc 280C Merc 450SE Merc 450SL Merc 450SLC
2.610223 2.835602 3.342705 3.539912 3.737119 3.610343 3.906153
Cadillac Fleetwood Lincoln Continental Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla Toyota Corona
4.582291 4.582291 3.976584 1.483327 1.765051 1.272034 3.018723
Dodge Challenger AMC Javelin Camaro Z28 Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
3.863894 3.906153 4.173791 3.342705 2.201723 2.384844 1.765051
Ford Pantera L Ferrari Dino Maserati Bora Volvo 142E
3.821636 3.272274 3.934325 3.032809
> residuals(lm.model) # 预测与实际之间的残差
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive Hornet Sportabout Valiant Duster 360
-0.46915365 -0.21415365 -0.51560210 0.18219114 0.02686382 -0.03765336 -0.46292884
Merc 240D Merc 230 Merc 280 Merc 280C Merc 450SE Merc 450SL Merc 450SLC
0.57977705 0.31439790 0.09729481 -0.09991195 0.33288129 0.11965707 -0.12615307
Cadillac Fleetwood Lincoln Continental Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla Toyota Corona
0.66770947 0.84170947 1.36841594 0.71667281 -0.15005113 0.56296577 -0.55372266
Dodge Challenger AMC Javelin Camaro Z28 Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
-0.34389448 -0.47115307 -0.33379081 0.50229481 -0.26672324 -0.24484380 -0.25205113
Ford Pantera L Ferrari Dino Maserati Bora Volvo 142E
-0.65163589 -0.50227421 -0.36432547 -0.25280886
> anova(lm.model) # anova table
Analysis of Variance Table
Response: wt
Df Sum Sq Mean Sq F value Pr(>F)
mpg 1 22.3431 22.3431 91.375 1.294e-10 ***
Residuals 30 7.3356 0.2445
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> vcov(lm.model) # 协方差矩阵
(Intercept) mpg
(Intercept) 0.095289963 -0.0043626666
mpg -0.004362667 0.0002171494
> influence(lm.model) # 相当与对分析的结果进行一个汇总
$hat
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive Hornet Sportabout Valiant Duster 360
0.03198439 0.03198439 0.03776901 0.03277255 0.03296737 0.03476902 0.06102792
Merc 240D Merc 230 Merc 280 Merc 280C Merc 450SE Merc 450SL Merc 450SLC
0.04774195 0.03776901 0.03195442 0.03590963 0.04334604 0.03816586 0.05249086
Cadillac Fleetwood Lincoln Continental Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla Toyota Corona
0.11464634 0.11464634 0.05705606 0.16580983 0.12563611 0.20060244 0.03301399
Dodge Challenger AMC Javelin Camaro Z28 Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
0.04996488 0.05249086 0.07220085 0.03195442 0.07740711 0.06226177 0.12563611
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本文介绍了R语言中的回归分析基础知识,包括线性回归的lm()函数及其评估,多元线性回归分析,以及多元非线性回归。文中详细探讨了glm()函数在非线性模型中的应用,还提到了使用earth和caret工具包进行机器学习回归分析,并展示了如何用nls和drm函数进行非线性最小二乘法拟合。同时,还讨论了如何评估自变量的重要性。
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