It seems like this should be consistent with split(), since that's what actually powers the behaviour.
Reading the description for split leads to this rather interesting example: tapply(mtcars, 1:11, I) Hadley On Tue, Feb 14, 2017 at 7:10 PM, Hervé Pagès <hpa...@fredhutch.org> wrote: > Hi, > > tapply() will work on any object 'X' that has a length and supports > single-bracket subsetting. These objects are sometimes called > "vector-like" objects. Atomic vectors, lists, S4 objects with a "length" > and "[" method, etc... are examples of "vector-like" objects. > > So instead of saying > > X: an atomic object, typically a vector. > > I think it would be more accurate if the man page was saying something > like > > X: a vector-like object that supports subsetting with `[`, typically > an atomic vector. > > H. > > > On 02/04/2017 04:17 AM, Tal Galili wrote: >> >> In the help page of ?tapply it says that the first argument (X) is "an >> atomic object, typically a vector." >> >> However, tapply seems to be able to handle list objects. For example: >> >> ################### >> >> l <- as.list(1:10) >> is.atomic(l) # FALSE >> index <- c(rep(1,5),rep(2,5)) >> tapply(l,index,unlist) >> >>> tapply(l,index,unlist) >> >> $`1` >> [1] 1 2 3 4 5 >> >> $`2` >> [1] 6 7 8 9 10 >> >> >> ################### >> >> Hence, does it mean a list an atomic object? (which I thought it wasn't) >> or >> is the help for tapply needs updating? >> (or some third option I'm missing?) >> >> Thanks. >> >> >> >> >> >> ----------------Contact >> Details:------------------------------------------------------- >> Contact me: tal.gal...@gmail.com | >> Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) | >> www.r-statistics.com (English) >> >> ---------------------------------------------------------------------------------------------- >> >> [[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. >> > > -- > Hervé Pagès > > Program in Computational Biology > Division of Public Health Sciences > Fred Hutchinson Cancer Research Center > 1100 Fairview Ave. N, M1-B514 > P.O. Box 19024 > Seattle, WA 98109-1024 > > E-mail: hpa...@fredhutch.org > Phone: (206) 667-5791 > Fax: (206) 667-1319 > > > ______________________________________________ > 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. -- http://hadley.nz ______________________________________________ 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.