renvironments

Assigning unknown variable to new variable name

I have to load in many files and tansform their data. Each file contains only one data.table, however the tables have various names.

I would like to run a single script over all of the files -- to do so, i must assign the unknown data.table to a common name ... say blob.

What is the R way of doing this? At present, my best guess (which seems like a hack, but works) is to load the data.table into a new environment, and then: assign('blob', get(objects(envir=newEnv)[1], env=newEnv).

In a reproducible context this is: 

newEnv <- new.env()
assign('a', 1:10, envir = newEnv)
assign('blob', get(objects(envir=newEnv)[1], env=newEnv))

Is there a better way?

Solution

  • I assume that you saved the data.tables using save() somewhat like this:

    d1 <- data.table(value=1:10)
save(d1, file="data1.rdata")

    and your problem is that when you load the file you don't know the name (here: d1) that you used when saving the file. Correct?

    I suggest you use instead saveRDS() and readRDS() for saving/loading single objects:

    d1 <- data.table(value=1:10)
saveRDS(d1, file="data1.rds")
blob <- readRDS("data1.rds")