Hi JD, On Sun, Sep 29, 2013 at 5:48 PM, john doe <anon.r.u...@gmail.com> wrote: > I am having trouble understanding how classes in R work. Here is a small > reproducable example: > >> x=1 >> class(x) > [1] "numeric" > > OK. When a variable is a number, its class is "numeric". Does R have > multiple types for numbers, like C++ (eg integer, float, double).
Yes, but the class is not the type: > x <- 1:10 > class(x) [1] "integer" > typeof(x) [1] "integer" > class(x) <- "foo" > class(x) [1] "foo" > typeof(x) [1] "integer" If so, > where can I see a list, and how does "numeric" fit into this system? A list of what? For a list of storage modes see ?typof. For classes there cannot be any such list, as you can create a new class as easily as class(x) <- "aNewClassThatNeverExistedBefore" > >> x=1:100 >> class(x) > [1] "integer" > > Wait - I thought that I assigned x to be an array/vector of 100 integers > (numerics). Why is the class not "array" or "vector". How is "integer" > different than "numeric"? Is there a "vector" or "array" class in R? If > so, why is this not that? See http://cran.r-project.org/doc/manuals/r-release/R-intro.html#Objects (And while you are there it wouldn't be a bad idea to read the rest of manual as well). > >> class(x[1]) > [1] "integer" > > This is even more confusing to me. Because x[1] is 1. And the class of > that was "numeric" in my first example. Why is it integer now? Presumably because '[' turned it into one. help("[") says that the return value is "typically an array-like R object of a similar class as ‘x’." > >> x=1.5:100.5 >> class(x) > [1] "numeric" > > Why is this class "numeric" when the class of 1:100 was integer? Because 1.5 is not an integer. See the Value section of help(":") > > Thanks for your help. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > 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. ______________________________________________ R-help@r-project.org mailing list 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.
