Collapse columns by grouping variable (in base)

Question

I have a text variable and a grouping variable. I\'d like to collapse the text variable into one string per row (combine) by factor. So as long as the group column says

Answer 1

I got the answer and came back to post but Dason beat me to it and more understandably than my own.

x <- rle(as.character(dat$group))[[1]]
dat$new <- as.factor(rep(1:length(x), x))

Paste <- function(x) paste(x, collapse=" ")
aggregate(text~new, dat, Paste)

EDIT How I'd do it with aggregate and what I learned from your response (though tapply is a better solution):

y <- rle(as.character(dat$group))
x <- y[[1]]
dat$new <- as.factor(rep(1:length(x), x))

text <- aggregate(text~new, dat, paste, collapse = " ")[, 2]
data.frame(text, group = y[[2]])