concatenation - Paste/Collapse in R

Question

I'm confused by paste, and thought it was just simple concatenating.

whales <- c("C","D","C","D","D")

quails <- c("D","D","D","D","D")

results <-paste(whales, quails, collapse = '')

Why would this return "C DD DC DD DD D" instead of CD DD CD DD DD?

Moreover, why would

results <-paste(whales[1], quails[1], collapse = '')

return

"C D" ?

with a space?

Thanks, D

EDIT

OK, I see that

results <-paste(whales, quails, collapse = NULL, sep='')

will get me what I want, but an explanation of why the previous code didn't work? And also thank you to the answerers.

Answer 1

For those who like visuals, here is my take at explaining how paste works in R:

sep creates element-wise sandwich stuffed with the value in the sep argument:

collapse creates ONE big sandwich with the value of collapse argument added between the sandwiches produced by using the sep argument: