Thank you, Gabor, Jim, and Achim!! All of your suggestions/pointers were extremely useful.
-----Original Message----- From: Gabor Grothendieck [mailto:[EMAIL PROTECTED] Sent: Thursday, January 10, 2008 7:46 PM To: Kondamani, Arjun (GMI - NY Corporate Bonds) Cc: r-help@r-project.org Subject: Re: [R] Extracting last time value Here is a slight variation of ones you have already received. This also uses zoo. In the DF<- line we read it in as a data frame. In the z<- line we convert it to zoo using chron date/times (see R News 4/1 for more). We calculate the positions of duplicate dates and in the last line we extract the rows corresponding to non-duplicates. Lines <- "Date time value 20110620 11:18:00 7 20110620 11:39:00 9 20110621 11:41:00 8 20110621 11:40:00 6 20110622 14:05:00 8 20110622 14:06:00 6 " library(zoo) library(chron) DF <- read.table(textConnection(Lines), header = TRUE, as.is = TRUE) z <- zoo(DF$value, chron(unclass(as.Date(format(DF$Date), "%Y%m%d"))), DF$time) isdup <- duplicated(dates(time(z)), fromLast = TRUE) z[!isdup,] For more on zoo see: library(zoo) vignette("zoo") vignette("zoo-quickref") On Jan 10, 2008 5:36 PM, Kondamani, Arjun (GMI - NY Corporate Bonds) <[EMAIL PROTECTED]> wrote: > I have a dataframe as follows: > > Date time value > 20110620 11:18:00 7 > 20110620 11:39:00 9 > 20110621 11:41:00 8 > 20110621 11:40:00 6 > 20110622 14:05:00 8 > 20110622 14:06:00 6 > > For every date, I want to extract the row that has the greatest time. > Therefore, ending up like: > 20110620 11:39:00 9 > 20110621 11:41:00 8 > 20110622 14:07:00 6 > > I am using for loops (for every date, find largest time value) to do > this determination, but I am sure there is a simpler way in "R". Has > anyone run into this before? > -------------------------------------------------------- > > This message w/attachments (message) may be privileged, confidential > or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or error-free. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. > -------------------------------------------------------- > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > -------------------------------------------------------- This message w/attachments (message) may be privileged, confidential or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or error-free. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. ______________________________________________ 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.
