Include an object within a function only if it exists - r

Question

I have a loop that needs to be executed; within which are 6 models. The objects that those models are stored in then need to get passed into a function that executes an AIC analysis. However, sometimes one of the models does not work, which then breaks the code for the AIC function because it does not recognize whatever model that failed because it was not stored as an object.
So, I need a way to pull those models that worked into the AIC function.
Here is an example, but keep in mind it is important that this can all be executed within a loop. Here are three hypothetical models:
hn.1 <- ds(data)
hn.1.obs <- ds(data,formula = ~OBSCODE)
hn.1.obs.mas <- ds(dataformula = ~OBSCODE+MAS)
And this would be my AIC function that compares the models:
summarize_ds_models(hn.1, hn.1.obs, hn.1.obs.mas)
But I get an error if say, the hn.1.obs.mas model failed.
I tried to use "get" and "ls" and I successfully pull the models that exist when I call:
get(ls(pattern='hn.15*'))
But that just returns a character vector, so that when I call:
summarize_ds_models(get(ls(pattern='hn.15*')))
it only conducts the AIC analysis on the first model in the above character vector.
Am I on the right track or is there a better way to do this?
UPDATE with a reproducible example.
Here is a simplified version of my problem:
create and fill two data frames that will be put into a list:
data.frame <- data.frame(x = integer(4),
y = integer(4),
z = integer(4),
i = integer(4))
data.frame$x <- c(1,2,3,4)
data.frame$y <- c(1,4,9,16)
data.frame$z <- c(1,3,8,10)
data.frame$i <- c(1,5,10,15)
data.frame.2 <- data.frame[1:4,1:3]
my.list <- list(data.frame,data.frame.2)
create df to fill with best models from AIC analyses
bestmodels <- data.frame(modelname = character(2))
Here is the function that will run the loop:
myfun <- function(list) {
for (i in 1:length(my.list)){
mod.1 = lm(y ~ x, data = my.list[[i]])
mod.2 = lm(y ~ x + z, data = my.list[[i]])
mod.3 = lm(y ~ i, data = my.list[[i]])
bestmodels[i,1] <- rownames(AIC(mod.1,mod.2,mod.3))[1]#bestmodel is 1st row
}
print(bestmodels)
}
However, on the second iteration of the loop, the AIC function will fail because mod.3 will fail. So, is there a generic way to make it so the AIC function will only execute for those models that worked? The outcome I would want here would be:
> bestmodels
modelname
1 mod.1
2 mod.1
since mod.1 would be chosen for both AIC analyses.

Answer 1

Gregor's comment:
Use a list instead of individual named objects. Then do.call(summarize_ds_models, my_list_of_models). If it isn't done already, you can Filter the list first to make sure only working models are in the list.
solved my problem. Thanks