How to append a vector to a list of vectors in R?

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This question related to an earlier one, except the answer there (use c() function) is precisely what was not working for me.

First I create a list of vectors and then an additional vector.

a_list <- lapply(mtcars, as.integer)
junk <- c(1:length(a_list[[1]]))

Now, if use c(a_list, junk) (as suggested in the answer to the earlier question), I get a completely different answer from what I get if I say a_list[["junk"]] <- junk (the latter yielding the desired result). It seems that what gets added by the former approach is as.list(junk).

How can I add junk using c() without it being converted to the result of as.list(junk)?

asked 31 secs ago

Ian Gow

188

1 Answer

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Use list() thus c(a_list, junk=list(junk)).

In trying to work out exactly what was being added in the problematic scenario above (to better formulate my question), I realized that list and as.list do very different things. By turning junk into a single-element list (using list()), it gets added "as is" in the desired fashion.

answered 31 secs ago

Ian Gow

188

How to append a vector to a list of vectors in R?