Re: [R] plyr: colvar value corresponding to max Date

Thank you A.K. and Ista. The answer that eliminates duplicated rows is A.K.'s first solution (brilliant idea using which.max!). The version of Ista's solution without duplicates is ddply(data, "state", function(x) x[which.max(x$date), ])$value Thanks again! Dan On Thu, Feb 13, 2014 at 8:36 AM, aru

Re: [R] plyr: colvar value corresponding to max Date

Hi, Try ?which.max() # unique values for the combination.  ddply(data,.(state),summarize,max_date=value[which.max(date)])[,2] #or  ddply(data,.(state),summarize,max_date=value[date == max(date)])[,2] A.K. On Thursday, February 13, 2014 11:15 AM, Dan Murphy wrote: I can do this in multiple st

Re: [R] plyr: colvar value corresponding to max Date

ddply(data, "state", function(x) x[x$date == max(x$date), ])$value On Thu, Feb 13, 2014 at 11:13 AM, Dan Murphy wrote: > I can do this in multiple steps with summarise, joins, etc., but can't > help thinking it can be accomplished in one plyr call. > > Here's a small example: > >> require(plyr) >

[R] plyr: colvar value corresponding to max Date

I can do this in multiple steps with summarise, joins, etc., but can't help thinking it can be accomplished in one plyr call. Here's a small example: > require(plyr) > require(lubridate) > data <- data.frame( + date = rep(as.Date(ymd(20140101 + (0:3) * 100)), 2), + state = rep(c("A", "B"), ea