R vif() 以及 step()

library(package="car")
data <- read.csv("C:\\users\\mike1\\desktop\\data\\RData\\hald水泥数据.csv", header=T, sep=",",fileEncoding = "utf-8", stringsAsFactors = FALSE)
data1 <- data[2:dim(data)[2]]
data1

cor(data1)
scatterplotMatrix(data1, main="correlation")

result <- lm(y~., data=data1)
summary(result)

vif(result)  # we can directly use the function not like python class
step(result,direction="forward")
step(result,direction="backward")
step(result, direction="both")

myStep <- step(result, direction="both")
myStep1 <- step(result,direction="backward",trace=2)


summary(myStep)
summary(myStep1)



vif(myStep)