Hi, Try: dat1<- read.table(text=" Date Time O H L C U D 06/01/2010 1358 136.40 136.40 136.35 136.35 2 12 06/01/2010 1359 136.40 136.50 136.35 136.50 9 6 06/01/2010 1400 136.45 136.55 136.35 136.40 8 7 06/01/2010 1700 136.55 136.55 136.55 136.55 1 0 06/02/2010 331 136.55 136.70 136.50 136.70 36 6 06/02/2010 332 136.70 136.70 136.65 136.65 3 1 06/02/2010 334 136.75 136.75 136.75 136.75 1 0 06/02/2010 335 136.80 136.80 136.80 136.80 4 0 06/02/2010 336 136.80 136.80 136.80 136.80 8 0 06/02/2010 337 136.75 136.80 136.75 136.80 1 2 06/02/2010 338 136.80 136.80 136.80 136.80 3 0 ",sep="",header=TRUE,stringsAsFactors=FALSE)
dat1[unlist(with(dat1,tapply(Time,list(Date),FUN=function(x) x==max(x)))),] # Date Time O H L C U D #4 06/01/2010 1700 136.55 136.55 136.55 136.55 1 0 #11 06/02/2010 338 136.80 136.80 136.80 136.80 3 0 #or dat1[cumsum(with(dat1,tapply(Time,list(Date),FUN=which.max))),] Date Time O H L C U D 4 06/01/2010 1700 136.55 136.55 136.55 136.55 1 0 11 06/02/2010 338 136.80 136.80 136.80 136.80 3 0 #or dat1[as.logical(with(dat1,ave(Time,Date,FUN=function(x) x==max(x)))),] # Date Time O H L C U D #4 06/01/2010 1700 136.55 136.55 136.55 136.55 1 0 #11 06/02/2010 338 136.80 136.80 136.80 136.80 3 0 A.K. ----- Original Message ----- From: Noah Silverman <noahsilver...@ucla.edu> To: "R-help@r-project.org" <r-help@r-project.org> Cc: Sent: Wednesday, August 14, 2013 3:56 PM Subject: [R] How to extract last value in each group Hello, I have some stock pricing data for one minute intervals. The delivery format is a bit odd. The date column is easily parsed and used as an index for an its object. However, the time column is just an integer (1:1807) I just need to extract the *last* entry for each day. Don't actually care what time it was, as long as it was the last one. Sure, writing a big nasty loop would work, but I was hoping that someone would be able to suggest a faster way. Small snippet of data below my sig. Thanks! -- Noah Silverman, M.S., C.Phil UCLA Department of Statistics 8117 Math Sciences Building Los Angeles, CA 90095 -------------------------------------------------------------------------- Date Time O H L C U D 06/01/2010 1358 136.40 136.40 136.35 136.35 2 12 06/01/2010 1359 136.40 136.50 136.35 136.50 9 6 06/01/2010 1400 136.45 136.55 136.35 136.40 8 7 06/01/2010 1700 136.55 136.55 136.55 136.55 1 0 06/02/2010 331 136.55 136.70 136.50 136.70 36 6 06/02/2010 332 136.70 136.70 136.65 136.65 3 1 06/02/2010 334 136.75 136.75 136.75 136.75 1 0 06/02/2010 335 136.80 136.80 136.80 136.80 4 0 06/02/2010 336 136.80 136.80 136.80 136.80 8 0 06/02/2010 337 136.75 136.80 136.75 136.80 1 2 06/02/2010 338 136.80 136.80 136.80 136.80 3 0 ______________________________________________ R-help@r-project.org mailing list 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 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.