[R] get latest dates for different people in a dataset

[Tan, Richard]

Thank you!

-----Original Message-----
From: David Barron [mailto:dnbarron at gmail.com] 
Sent: Saturday, January 24, 2015 7:56 AM
To: Tan, Richard; r-help at R-project.org
Subject: Re: [R] get latest dates for different people in a dataset

Hi Richard,

You could also do it using the package dplyr:

dta <- data.frame(Name=c('John','Mary','Sam','John'),

CheckInDate=as.Date(c('1/3/2014','1/3/2014','1/4/2014','1/4/2014'),
                                      format='%d/%m/%Y'),
                  Temp=c(97,98.1,97.5,99))


library(dplyr)
dta %>% group_by(Name)  %>% filter(CheckInDate==max(CheckInDate))

Source: local data frame [3 x 3]
Groups: Name

  Name CheckInDate Temp
1 Mary  2014-03-01 98.1
2  Sam  2014-04-01 97.5
3 John  2014-04-01 99.0

On 24 January 2015 at 01:09, Chel Hee Lee <chl948 at mail.usask.ca> wrote:
>> do.call(rbind, lapply(split(data, data$Name), function(x)
>> x[order(x$CheckInDate),][nrow(x),]))
>      Name CheckInDate Temp
> John John  2014-04-01 99.0
> Mary Mary  2014-03-01 98.1
> Sam   Sam  2014-04-01 97.5
>>
>
> Is this what you are looking for?  I hope this helps.
>
> Chel Hee Lee
>
>
> On 01/23/2015 05:43 PM, Tan, Richard wrote:
>>
>> Hi,
>>
>> Can someone help for a R question?
>>
>> I have a data set like:
>>
>> Name    CheckInDate      Temp
>> John      1/3/2014              97
>> Mary     1/3/2014              98.1
>> Sam       1/4/2014              97.5
>> John      1/4/2014              99
>>
>> I'd like to return a dataset that for each Name, get the row that is 
>> the latest CheckInDate for that person.  For the example above it 
>> would be
>>
>> Name    CheckInDate      Temp
>> John      1/4/2014              99
>> Mary     1/3/2014              98.1
>> Sam       1/4/2014              97.5
>>
>>
>> Thank you for your help!
>>
>> Richard
>>
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see 
>> 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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see 
> 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.