I have a dataframe with some columns with data plus a column containing column names:
mydf <- data.frame(
"aa" = 11:15,
"ab" = 21:25,
"ac" = 31:35,
"nn" = c("aa", "aa", "ac", "ab", "aa"))
I would like to get a vector from columns "aa", "ab", or "ac". That column name for every row is specified in the "nn" column.
So I should get 11, 12, 33, 24, 15.
Can this be done without loops? mydf[mydf$nn] does not work.