R: can `assign` be used for models? - r

Question

Can the assign function in R be used to assign object names to models (e.g., gls models)? I'm guessing not b/c I keep getting a warning:
> Warning messages:
In assign(paste0(deparse(substitute(mod)), "_", i, j), update(mod, :
only the first element is used as variable name
As a result the objects are not created
Is there a way to do this?
Here is my fucntion code if it helps:
#Choose best corARMA structure for model of choice:
corARMA.chooser <- function(mod,min = 0,max = 3 ) {
#This function creates 1. object for each combo of ARMA {0:3} 2. AIC table comparing all of these models
mod <- get('mod')
aic.arma <- AIC(mod)
ps <- 0
qs <- 0
for(i in min:max) {
js <- if(i == 0) c(1:max) else c(min:max)
for(j in js) {
arma <- corARMA(p = i, q = j)
assign(paste0(deparse(substitute(mod)),'_',i,j), update(mod, .~., correlation = arma), envir = .GlobalEnv)
aic.arma <- c(aic.arma, AIC(get(paste0(deparse(substitute(mod)),'_',i,j))))
ps <- c(ps, i)
qs <- c(qs, i)
}
aic.arma.out <- data.frame(ps, qs, aic.arma)
aic.arma.out
}
}
Update:
I tried using the list approach, but I get the error:
Error in names(mod.list) <- c(names(mod.list), paste0(deparse(substitute(mod)), :
'names' attribute [1275] must be the same length as the vector [1]

Answer 1

EDIT: what actually tears your variable name apart is this line mod <- get('mod') where you overwrite your named instance of mod why do you actually do this? If change your function to this it behaves as I'd expect it to:
corARMA.chooser <- function(modIn,min = 0,max = 3 ) {
#This function creates 1. object for each combo of ARMA {0:3} 2. AIC table comparing all of these models mod <- get('modIn') aic.arma <- AIC(modIn) ps <- 0 qs <- 0 for(i in min:max) {
js <- if(i == 0) c(1:max) else c(min:max)
for(j in js) {
arma <- corARMA(p = i, q = j)
browser()
assign(paste0(deparse(substitute(modIn)),'_',i,j), update(mod, .~., correlation = arma), envir = .GlobalEnv)
aic.arma <- c(aic.arma, AIC(get(paste0(deparse(substitute(mod)),'_',i,j))))
ps <- c(ps, i)
qs <- c(qs, i)
}
aic.arma.out <- data.frame(ps, qs, aic.arma)
aic.arma.out
}
}
hope this is what you were trying to achieve.

Answer 2

Still not sure why the code works alone but not in the function, but it is clear that the deparse(substitute(mod)) is for some reason pulls mod apart to all of its parts first in the function, vs. simply creating a name of the object itself.
Here is my new code that works:
corARMA.chooser <- function(mod,p = 1,q = 0 ) {
#This function creates 1. object for each combo of ARMA {0:3} 2. AIC table comparing all of these models
mod.list <- NULL
nms <- NULL
aic.arma <- AIC(mod)
ps <- 0
qs <- 0
for(i in c(p)) {
js <- if(i == 0) c(q[q>0]) else c(q)
for(j in c(js)) {
arma <- corARMA(p = i, q = j)
mod.list <- c(mod.list, list(update(mod, .~., correlation = arma)))
names(mod.list) <- c(names(mod.list), paste0(deparse(substitute(mod)),'_',i,j))
aic.arma <- c(aic.arma, AIC(eval(parse(text=(paste0('mod.list$',deparse(substitute(mod)),'_',i,j))))))
ps <- c(ps, i)
qs <- c(qs, j)
}
}
assign(paste0(deparse(substitute(mod)),'_','ARMA'),mod.list, envir = .GlobalEnv)
aic.arma.out <- data.frame(p = ps, q = qs, AIC = aic.arma)
aic.arma.out
}