Hi Jeff,
We are splitting hairs because R is splitting hairs, and causing us problems. Integer and numeric are different R classes with different properties, mathematical relationships notwithstanding. For instance, the counterintuitive result: > identical(as.integer(1), as.numeric(1)) [1] FALSE Unfortunately the reply-to chain doesn't extend far enough -- here is the original problem: > sapply(1, identical, 1) [1] TRUE > sapply(1:2, identical, 1) [1] FALSE FALSE > sapply(1:2, function(i) identical(as.numeric(i),1) ) [1] TRUE FALSE > sapply(1:2, function(i) identical(as(i,"numeric"),1) ) [1] FALSE FALSE These are the results of R's hair-splitting! Ariel ________________________________ From: Jeff Newmiller <jdnew...@dcn.davis.ca.us> Sent: Monday, April 11, 2016 6:49 PM To: Bert Gunter; Paulson, Ariel Cc: Rolf Turner; r-help@r-project.org Subject: Re: [R] [FORGED] Re: identical() versus sapply() Hypothesis regarding the thought process: integer is a perfect subset of numeric, so why split hairs? -- Sent from my phone. Please excuse my brevity. On April 11, 2016 12:36:56 PM PDT, Bert Gunter <bgunter.4...@gmail.com> wrote: Indeed! Slightly simplified to emphasize your point: class(as(1:2,"numeric")) [1] "integer" class(as.numeric(1:2)) [1] "numeric" whereas in ?as it says: "Methods are pre-defined for coercing any object to one of the basic datatypes. For example, as(x, "numeric") uses the existing as.numeric function. " I suspect this is related to my ignorance of S4 classes (i.e. as() ) and how they relate to S3 classes, but I certainly don't get it either. 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 Mon, Apr 11, 2016 at 9:30 AM, Paulson, Ariel <a...@stowers.org> wrote: Ok, I see the difference between 1 and 1:2, I'll just leave it as one of those "only in R" things. But it seems then, that as.numeric() should guarantee a FALSE outcome, yet it does not. To build on what Rolf pointed out, I would really love for someone to explain this one: str(1) num 1 str(1:2) int [1:2] 1 2 str(as.numeric(1:2)) num [1:2] 1 2 str(as(1:2,"numeric")) int [1:2] 1 2 Which doubly makes no sense. 1) Either the class is "numeric" or it isn't; I did not call as.integer() here. 2) method of recasting should not affect final class. Thanks, Ariel -----Original Message----- From: Rolf Turner [mailto:r.tur...@auckland.ac.nz] Sent: Saturday, April 09, 2016 5:27 AM To: Jeff Newmiller Cc: Paulson, Ariel; 'r-help@r-project.org' Subject: Re: [FORGED] Re: [R] identical() versus sapply() On 09/04/16 16:24, Jeff Newmiller wrote: I highly recommend making friends with the str function. Try str( 1 ) str( 1:2 ) Interesting. But to me counter-intuitive. Since R makes no distinction between scalars and vectors of length 1 (or more accurately I think, since in R there is *no such thing as a scalar*, only a vector of length 1) I don't see why "1" should be treated in a manner that is categorically different from the way in which "1:2" is treated. Can you, or someone else with deep insight into R and its rationale, explain the basis for this difference in treatment? for the clue you need, and then sapply( 1:2, identical, 1L ) cheers, Rolf -- Technical Editor ANZJS Department of Statistics University of Auckland Phone: +64-9-373-7599 ext. 88276 ________________________________ 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. [[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.
