What is the use of 'sep' in paste command of R?

Question

I was working with the paste command in R, when I found that

a <- c("something", "to", "paste")  
paste(a, sep="_")

produces the output

# [1] "something" "to" "paste"

Which is same as when I print "a"

# [1] "something" "to" "paste"

So what effect does the sep have on the paste command in R?

Try `paste("something", "to", "paste", sep = "_")` (without the `c`) — David Arenburg, Nov 25 '14 at 10:01
Try paste(a[1],a[2],a[3],sep='_'). The problem is you are only passing one item, not three. — , Nov 25 '14 at 10:04
I'm just trying to illustrate what the problem is, paste(a,sep='_') doesn't paste "a" to anything. But, I don't do anything serious anymore.... — , Nov 25 '14 at 10:06

score 4 · Accepted Answer · answered Nov 25 '14 at 10:00

sep is more generally applicable when you have more than two vectors of length greater than 1. If you were looking to get "something_to_paste", then you would be looking for the collapse argument.

Try the following to get a sense of what the sep argument does:

paste(a, 1:3, sep = "_")
# [1] "something_1" "to_2"        "paste_3"

and compare it to collapse:

paste(a, collapse = "_")
# [1] "something_to_paste"

What is the use of 'sep' in paste command of R?

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