How to quickly add quotes and commas to a list of items for c() in R?

Question

This is a matter of convenience more than anything. I'm often adding quotes and commas by hand to make a c() list for some other function. Is there a quick and clever way to add them that doesn't involve tricky find/replaces or multiple operations? If I have multiple items separated by a space or tab, or one item per line I'd like to do the following:

A B C D

or

A

B

C

D

to:

temp <- c("A", "B", "C", "D")

I can add them by hand, do a find/replace for the whitespace to ", " and then add in the first/last, but that is annoying. Is there a quicker way?

Answer 1

The scan function is the basis for all the read.* functions, but it also serves to execute the task you desire executed. A couple of years ago a text parameter was added so you no longer need to wrap textConnection around "naked strings". Can be used with any delimiter and the default whitespace delimiter will handle what yopu ask to be processed:

 TEMP <- scan(text="A B C D", what="")

#-------------------
Read 4 items
> TEMP
[1] "A" "B" "C" "D"
> dput(TEMP)
c("A", "B", "C", "D")

If you need to maintain leading zeros on what might be numeric, then you will need to either import them as text or prepend the leading zeros when printing them with formatC or sprintf