On Thu, Jan 28, 2010 at 11:21 AM, Duncan Murdoch <murd...@stats.uwo.ca> wrote: > On 28/01/2010 5:30 AM, Benilton Carvalho wrote: >> >> Hi Duncan, >> >> On Tue, Jan 26, 2010 at 9:09 PM, Duncan Murdoch <murd...@stats.uwo.ca> >> wrote: >>> >>> On 26/01/2010 3:25 PM, Blanford, Glenn wrote: >>>> >>>> Has there been any update on R's handling large integers greater than >>>> 10^9 >>>> (between 10^9 and 4x10^9) ? >>>> >>>> as.integer() in R 2.9.2 lists this as a restriction but doesnt list the >>>> actual limit or cause, nor if anyone was looking at fixing it. >>> >>> Integers in R are 4 byte signed integers, so the upper limit is 2^31-1. >>> That's not likely to change soon. >> >> But in the hypothetical scenario that this was to change soon and we >> were to have 64bit integer type (say, when under a 64 bit OS), >> wouldn't this allow us to have objects whose length exceeded the >> 2^31-1 limit? > > Those are certainly related problems, but you don't need 64 bit integers to > have longer vectors. We could switch to indexing by doubles in R (though > internally the indexing would probably be done in 64 bit ints). > > A problem with exposing 64 bit ints in R is that they break the rule that > doubles can represent any integer exactly. If x is an integer, x+1 is a > double, and it would be unfortunate if (x+1) != (x+1L), as will happen with > values bigger than 2^52.
I see... thanks for the clarification. I'm sure that changes like this would bring several side effects, but regardless how they're done I believe they would benefit the whole community. As an example, with a BioC package I wrote, we can "only" analyze roughly 2K samples on a given microarray platform (despite the fact that we have way more than 2K samples). In the meantime, we have to use other tricks to work around the 2^31-1 limit. Again, thank you very much, Benilton Carvalho > > Duncan Murdoch > > >> >> >> Benilton Carvalho >> >> >> >> >>> The double type in R can hold exact integer values up to around 2^52. So >>> for >>> example calculations like this work fine: >>> >>>> x <- 2^50 >>>> y <- x + 1 >>>> y-x >>> >>> [1] 1 >>> >>> Just don't ask R to put those values into a 4 byte integer, they won't >>> fit: >>> >>>> as.integer(c(x,y)) >>> >>> [1] NA NA >>> Warning message: >>> NAs introduced by coercion >>> >>> Duncan Murdoch >>> >>>> Glenn D Blanford, PhD >>>> <mailto:glenn.blanf...@us.army.mil> >>>> Scientific Research Corporation >>>> gblanf...@scires.com<mailto:gblanf...@scires.com> >>>> >>>> >>>> [[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. >>> > > ______________________________________________ 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.
