I should have formulated my question in a more specific way. 1. I suspect this is a floating point precision issue. I am not very knowledgeable about R internals, can someone else confirm it?
2. Should this be considered a bug or not, because it is "just a precision issue"? Should I report it? 3. How can it happen? From a quick review of ts.R, it looks like the values of the time index are never modified, but only possibly removed. In my case: - x and y have the same index. - the subtraction operator recognizes this, and create a new ts with one entry - the result of the subtraction has an index which is different from the input. This is very surprising to me, and I am curious to understand the problem. -- Andrea Altomani On Fri, Sep 1, 2017 at 5:53 PM Jeff Newmiller <jdnew...@dcn.davis.ca.us> wrote: > You already know the answer. Why ask? > -- > Sent from my phone. Please excuse my brevity. > > On September 1, 2017 7:23:24 AM PDT, Andrea Altomani < > altomani.and...@gmail.com> wrote: > >I have a time series x, and two other series obtained from it: > > > >x <- structure(2017, .Tsp = c(2017.41666666667, 2017.41666666667, 12), > >class = "ts") > >y <- floor(x) > >z <- x-y > > > >I would expect the three series to have exactly the same index. > >However I get the following > > > >> time(x)-time(y) > > Jun > >2017 0 > > > >as expected, but > > > >> time(x)-time(z) > >integer(0) > >Warning message: > >In .cbind.ts(list(e1, e2), c(deparse(substitute(e1))[1L], > >deparse(substitute(e2))[1L]), : > > non-intersecting series > > > >and indeed, comparing the indices gives: > > > >> time(x)[1]-time(z)[1] > >[1] 3.183231e-12 > > > >Is this a bug in R, or is it one of the expected precision errors due > >to the use of limited precision floats? > > > >I am using R 3.4.0 (2017-04-21) on Windows (64-bit). > > > >Thaks! > > > >Andrea Altomani > > > >______________________________________________ > >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.
