Sorry, that should be > id <- c(1,2,2,2,3,4,5,5) > last.index <- cumsum(rle(id)$lengths) > last.index [1] 1 4 5 6 8
of course. Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Thu, Sep 9, 2021 at 12:20 PM Bert Gunter <bgunter.4...@gmail.com> wrote: > > Many ways to do this, of course, but if I understand correctly ?rle > may be the simplest, because you already have the data sorted by ID. > > The following little example should give you the idea. It gets the > index of the last row in each id,, which you can then use to assign > NA's or whatever: > > > id <- c(1,2,2,2,3,4,5,5) > > last.index <- cumsum(rle(test)$lengths) > > last.index > [1] 1 4 5 6 8 > > 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 Thu, Sep 9, 2021 at 12:00 PM Kai Yang via R-help > <r-help@r-project.org> wrote: > > > > Hello List, > > Please look at the sample data frame below: > > > > ID date1 date2 date3 > > 1 2015-10-08 2015-12-17 2015-07-23 > > > > 2 2016-01-16 NA 2015-10-08 > > 3 2016-08-01 NA 2017-01-10 > > 3 2017-01-10 NA 2016-01-16 > > 4 2016-01-19 2016-02-24 2016-08-01 > > 5 2016-03-01 2016-03-10 2016-01-19 > > This data frame was sorted by ID and date1. I need to set the column date3 > > as missing for the "last" record for each ID. In the sample data set, the > > ID 1, 2, 4 and 5 has one row only, so they can be consider as first and > > last records. the data3 can be set as missing. But the ID 3 has 2 rows. > > Since I sorted the data by ID and date1, the ID=3 and date1=2017-01-10 > > should be the last record only. I need to set date3=NA for this row only. > > > > the question is, how can I identify the "last" record and set it as NA in > > date3 column. > > Thank you, > > Kai > > [[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. ______________________________________________ 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.
