Thanks Hadley! While I got your attention, what is a good way to get started on ggplot2? ;)
My impression is that I first need to learn plyr, dplyr, AND THEN ggplot2. That's A LOT! Suppose i have this: iris iris2 <- cbind(iris, grade = sample(1:5, 150, replace = TRUE)) iris2 I want to have some kind of graph conditioned on species, by grade . What's a good lead to learn about plotting this? Thank you! On Mon, Feb 20, 2017 at 11:12 AM, Hadley Wickham <h.wick...@gmail.com> wrote: > On Sun, Feb 19, 2017 at 3:01 PM, David Winsemius <dwinsem...@comcast.net> > wrote: > > > >> On Feb 19, 2017, at 11:37 AM, C W <tmrs...@gmail.com> wrote: > >> > >> Hi R, > >> > >> I am a little confused by the data.table package. > >> > >> library(data.table) > >> > >> df <- data.frame(w=rnorm(20, -10, 1), x= rnorm(20, 0, 1), y=rnorm(20, > 10, 1), > >> z=rnorm(20, 20, 1)) > >> > >> df <- data.table(df) > > > > df <- setDT(df) is preferred. > > Don't you mean just > > setDT(df) > > ? > > setDT() modifies by reference. > > >> > >> df_3 <- df[, a := x-y] # created new column a using x minus y, why are > we > >> using colon equals? > > > > You need to do more study of the extensive documentation. The behavior > of the ":=" function is discussed in detail there. > > You can get to that documentation with ?":=" > > Hadley > > -- > http://hadley.nz > [[alternative HTML version deleted]] ______________________________________________ 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.
