Question

I’m trying to use get() to access a list element in R, but am getting an error.

example.list <- list()
example.list$attribute <- c("test")
get("example.list") # Works just fine
get("example.list$attribute") # breaks

## Error in get("example.list$attribute") : 
##  object 'example.list$attribute' not found

Any tips? I am looping over a vector of strings which identify the list names, and this would be really useful.

Answer 1

Here’s the incantation that you are probably looking for:

get("attribute", example.list)
# [1] "test"

Or perhaps, for your situation, this:

get("attribute", eval(as.symbol("example.list")))
# [1] "test"

# Applied to your situation, as I understand it...

example.list2 <- example.list 
listNames <- c("example.list", "example.list2")
sapply(listNames, function(X) get("attribute", eval(as.symbol(X))))
# example.list example.list2 
#       "test"        "test"