How can I replicate this loop with apply in R? - r

Question

I have been learning how to code in R recently, so I'm not familiarized with apply at all. As far as I know loops are not so efficient in R, so I'm trying to use apply function but I'm not getting any results.
This is my loop:
encoder_output <- function(sequence, vocabulary){
auxlist <- list()
for (i in sequence) {
encoded <- to_categorical(i, num_classes=vocabulary)
auxlist <- append(auxlist, encoded)
}
arrOutput <- array(unlist(auxlist),dim =c(nrow(sequence),ncol(sequence),vocabulary))
return(arrOutput)
}
And here is my apply:
encode_output <- function(sequence, vocabulary){
auxlist <- list()
apply(sequence, 1,function(x){
encoded <- to_categorical(x, num_classes=vocabulary)
auxlist <- append(auxlist, encoded)
})
array <- array(unlist(auxlist), dim= c(nrow(sequence),ncol(sequence),vocabulary) )
return(array)
}
But in my apply function, I'm getting an error in unlist, because it says that auxlist is empty.
I don't know what I'm doing wrong. Btw, sequence is a 2D matrix. I believe that this code is enough to solve my question, but if necessary I will update it with more code.
Thanks guys!
PS: I'm using keras library to user to_categorical.

Answer 1

Ah. This is the classic coding environment issue. The return function will only give you a result within the code, but not show up in your environment. So try this:
assign(New_array_Name,array = df,.GlobalEnv)
Another way to do it is to have it as an output to assign it to another 'external' variable. In this case, remove return(arrOutput), replace it with arrOutput. And, in the console or wherever you run your code, use the following line.
variable <- encoder_output(...)