[R] Extracting last time value

[jim holtman]

This should do it:

> x <- read.table(textConnection("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"), header=TRUE, as.is=TRUE)
>
> x$time <- as.POSIXct(strptime(x$time, "%H:%M:%S"))
> do.call(rbind, lapply(split(x, x$Date), function(.day){
+     .day[which.max(.day$time),]
+ }))
             Date                time value
20110620 20110620 2008-01-10 11:39:00     9
20110621 20110621 2008-01-10 11:41:00     8
20110622 20110622 2008-01-10 14:06:00     6
>


On Jan 10, 2008 5:36 PM, Kondamani, Arjun (GMI - NY Corporate Bonds)
<arjun_kondamani at ml.com> 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 at 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.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?