There is no good example code online of how to do forward selection with MASS::stepAIC and that's really annoying

stepAIC forward example.R

#So here's an example of that


x<-rnorm(100)
y<-rnorm(100)
z<-rnorm(100)
xy<-x+2*y+rnorm(100)

# everything needs to be in a dataframe
data<-data.frame(xy,x,y,z)

# stepAIC is in MASS
library(MASS)

# need to define the starting model
initialModel<-lm(xy~1,data)

# need to define the model with all parameters
allModel<-lm(xy~.,data)

# now we can do stepAIC
stepAIC(initialModel,direction="forward",
    scope=list(lower=initialModel,
        upper=allModel)
    )