r - Generate an accumulated array of strings from a string array -

i have this:

str <- c("var1", "var2", "var3") 

and want generate following array of strings:

"c ~ var1" "c ~ var1 + var2" "c ~ var1 + var2 + var3" 

i know can hardcode this, since there 3 strings, want method vector of size. there simple way achieve this?

you try this:

out <- vector() out[1] <- paste("c ~",str[1]) (i in 2:length(str)) out[i] <- paste(out[i-1], "+", str[i])