[R] adding columns to dataframes contained in a list

E Hofstadler
Wed, 04 May 2011 07:25:06 -0000

hi there,

I have a list of 5 identical dataframes:

mydf <- data.frame(x=c(1:5), y=c(21:25))
mylist <- rep(list(mydf),5)

and a factor variable with 5 levels:

foo <- c(letters[1:5])
foo <- as.factor(foo)


Question:
I'd like to add a new variable to each dataframe in the list, each
containing only one level of the factor variable. So mylist[[1]]
should have a new variable z containing only "a", in mylist[[2]]  the
new variable z should contain only "b", etc.

(How) can this be done without looping?

All help is greatly appreciated.

Best,
Esther