Use list indexing, "[[" not "[" . > df <- data.frame(a=1:3,b=letters[1:3]) > x <- "new" > df[[x]]<- I(list(1:5,g = "foo", abb = matrix(runif(6),nr=3))) > df a b new 1 1 a 1, 2, 3,.... 2 2 b foo 3 3 c 0.248115.... > df$new [[1]] [1] 1 2 3 4 5
$g [1] "foo" $abb [,1] [,2] [1,] 0.2481156 0.2138564 [2,] 0.8598658 0.2898058 [3,] 0.5854885 0.4084578 Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Sun, Dec 11, 2016 at 3:54 AM, Marlin JL.M <marl...@gmx.cn> wrote: > > If you see my previous example, I have tried something like >> df[,n3] <- I(mylist) > > However, in my case, the name of the new column is in a variable (by > user input) which can not be directly used by the dollar assign. On the > other hand, "[<-" does not work correctly even if I wrap the list into > "I()". > > Perhaps the title of my email is a little unclear, sorry for the case. > > Best, > Marlin. > > On Sun, 2016-12-11 at 03:03 -0800, Bert Gunter wrote: >> ?data.frame says: >> >> "If a list or data frame or matrix is passed to data.frame it is as >> if >> each component or column had been passed as a separate argument >> (except for matrices of class "model.matrix" and those protected by >> I). " >> >> So doing what Help says to do seems to do what you asked: >> >> >> > df <- data.frame(a=1:3,b=letters[1:3]) >> > df >> >> a b >> 1 1 a >> 2 2 b >> 3 3 c >> >> ## add a list column, protected by "I()" >> > df$new <- I(list(1:5,g = "foo", abb = matrix(runif(6),nr=3))) >> >> ## works as advertised >> > df >> >> a b new >> 1 1 a 1, 2, 3,.... >> 2 2 b foo >> 3 3 c 0.080349.... >> >> > df$new >> >> [[1]] >> [1] 1 2 3 4 5 >> >> $g >> [1] "foo" >> >> $abb >> [,1] [,2] >> [1,] 0.08034915 0.83671591 >> [2,] 0.43938440 0.06067429 >> [3,] 0.88196881 0.33461234 >> >> >> Cheers, >> Bert >> >> >> Bert Gunter >> >> "The trouble with having an open mind is that people keep coming >> along >> and sticking things into it." >> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >> >> >> On Sat, Dec 10, 2016 at 7:18 PM, Marlin JL.M <marl...@gmx.cn> wrote: >> > Dear all, >> > >> > I want to assign a list to one column of data.frame where the name >> > of the column >> > is a variable. I tried the following: >> > >> > Using R version 3.3.2 >> > >> > > df <- iris[1:3, ] >> > > df >> > >> > # Sepal.Length Sepal.Width Petal.Length Petal.Width Species >> > # 1 5.1 3.5 1.4 0.2 setosa >> > # 2 4.9 3.0 1.4 0.2 setosa >> > # 3 4.7 3.2 1.3 0.2 setosa >> > >> > > mylist <- list(c(1,2,3),c(1),c()) >> > > mylist >> > >> > # [[1]] >> > # [1] 1 2 3 >> > # >> > # [[2]] >> > # [1] 1 >> > # >> > # [[3]] >> > # NULL >> > >> > > n1 <- 'new1' >> > > df$n1 <- mylist >> > > n2 <- 'new2' >> > > df[,n2] <- mylist >> > >> > # Warning message: >> > # In `[<-.data.frame`(`*tmp*`, , "new4", value = list(c(1, 2, >> > 3), : >> > # provided 3 variables to replace 1 variables >> > >> > > n3 <- 'new3' >> > > df[,n3] <- I(mylist) >> > >> > # Warning message: >> > # In `[<-.data.frame`(`*tmp*`, , "new3", value = list(c(1, 2, >> > 3), : >> > # provided 3 variables to replace 1 variables >> > >> > > eval(parse(text = paste0("df$","new4","<- mylist"))) >> > > df >> > >> > # Sepal.Length Sepal.Width Petal.Length Petal.Width Species n1 >> > new2 new3 new4 >> > # 1 5.1 3.5 1.4 0.2 setosa 1, 2, >> > 3 1 1 1, 2, 3 >> > # >> > 2 4.9 3.0 1.4 0.2 setosa 1 >> > 2 2 1 >> > # >> > 3 4.7 3.2 1.3 0.2 setosa NULL >> > 3 3 NULL >> > >> > >> > The "eval" works correctly, however, if I want to avoid using >> > "eval", what >> > should I do? >> > >> > Thanks! >> > >> > ______________________________________________ >> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> > https://stat.ethz.ch/mailman/listinfo/r-help >> > PLEASE do read the posting guide http://www.R-project.org/posting-g >> > uide.html >> > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.