difference of two rows
Try this:
x <- read.table(textConnection("ID YEAR
+ 13 2007 + 15 2003 + 15 2006 + 15 2008 + 21 2006 + 21 2007"), header=TRUE)
x$diff <- ave(x$YEAR, x$ID, FUN=function(a) c(diff(a), NA)) x
ID YEAR diff 1 13 2007 NA 2 15 2003 3 3 15 2006 2 4 15 2008 NA 5 21 2006 1 6 21 2007 NA
On Wed, Nov 25, 2009 at 10:55 AM, clion <birte_2 at hotmail.com> wrote:
Dear R user, I'd like to calculate the difference of two rows, where "ID" is the same. eg.: I've got the following dataframe: ID YEAR 13 2007 15 2003 15 2006 15 2008 21 2006 21 2007 and I'd like to get the difference, like this: ID YEAR ? ? diff 13 2007 ? ? ?NA 15 2003 ? ? ? 3 15 2006 ? ? ? 2 15 2008 ? ? ?NA 21 2006 ? ? ? 1 21 2007 ? ? ?NA that should be fairly easy...I hope Thanks for any helpful comments B. -- View this message in context: http://old.nabble.com/difference-of-two-rows-tp26515212p26515212.html Sent from the R help mailing list archive at Nabble.com.
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