I know this question has been raised before (Error in <my code> : object of type 'closure' is not subsettable). But I could not get my head around it.
Here is the packages I use and how I prepare my data
library(mlogit)
data(CollegeDistance, package="AER")
Data <- CollegeDistance
Data$Dist[Data$distance<0.4] <- 1
Data$Dist[Data$distance<1 & Data$distance>=0.4] <- 2
Data$Dist[Data$distance<2.5 & Data$distance>=1] <- 3
Data$Dist[Data$distance>=2.5] <- 4
Now when I define a mlogit object and use it for prediction I get that error.
Formula <- paste('Dist ~', paste('1|',paste(c("urban", "unemp", "tuition"), collapse = " + "),'|1'))
Model <- mlogit(as.formula(Formula), Data, shape='wide', choice='Dist')
Predict <- predict(Model, newdata=mlogit.data(Data, shape='wide', choice='Dist'), returnData=FALSE)
The interesting part is that if I replace Formula with formulathen it works!
UPDATE
I encounter that problem while using mlogit in a function. I really appreciate it if you can show me a way out of it.
modelmaker <- function(variables){
Formula <- paste('Dist ~', paste('1|',paste(variables, collapse = " + "),'|1'))
MODEL <- mlogit(as.formula(Formula), Data, shape='wide', choice='Dist')
return(MODEL)
}
Model <- modelmaker(c("urban", "unemp", "tuition"))
Predict <- predict(Model, newdata=mlogit.data(Data, shape='wide', choice='Dist'), returnData=FALSE)
This time is does not solve even by avoiding using formula or Formula. If you change it to XXX the error will be
object 'XXX' not found
