Hi, Nice reproducible example.
rev(df$date2) isn't doing what you think it's doing - try looking at it by itself. Some digging into ?order will get you what you are after: df[order(df$ID, df$date2, decreasing=c(FALSE, TRUE), method="radix"),] > df[order(df$ID, df$date2, decreasing=c(FALSE, TRUE), method="radix"),] ID date2 2 A1 2005-01-27 1 A1 2004-09-17 3 A1 2003-05-07 4 A2 2017-05-21 5 A2 2016-09-12 6 A3 2013-01-25 7 A4 2019-09-27 Sarah On Mon, Sep 21, 2020 at 2:41 PM Val <valkr...@gmail.com> wrote: > > Hi All, > > I am trying to sort dates within a group. My sample data is > > df <-read.table(text="ID date > A1 09/17/04 > A1 01/27/05 > A1 05/07/03 > A2 05/21/17 > A2 09/12/16 > A3 01/25/13 > A4 09/27/19",header=TRUE,stringsAsFactors=F) > df$date2 = as.Date(strptime(df$date,format="%m/%d/%y")) > df$date =NULL > > I want to sort date2 from recent to oldest. within the ID group and > I used this, > df <- df[order(df$ID, rev((df$date2))),]. It did not work and teh > output is shown below. > > ID date2 > 2 A1 2005-01-27 > 3 A1 2003-05-07 > 1 A1 2004-09-17 > 5 A2 2016-09-12 > 4 A2 2017-05-21 > 6 A3 2013-01-25 > 7 A4 2019-09-27 > What am I missing? > Thank you. > > ______________________________________________ > 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. -- Sarah Goslee (she/her) http://www.numberwright.com ______________________________________________ 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.
