On 2015-01-24 01:14, William Dunlap wrote:
Here is one way. Sort the data.frame, first by Name then break ties with
CheckInDate.
Then choose the rows that are the last in a run of identical Name values.
I do it by sorting by the reverse order of CheckinDate (last date first)
within Name, then
> dLatestVisit <- dSorted[!duplicated(dSorted$Name), ]
I guess it is faster, but who knows?
Göran
txt <- "Name CheckInDate Temp
+ John 1/3/2014 97
+ Mary 1/3/2014 98.1
+ Sam 1/4/2014 97.5
+ John 1/4/2014 99"
d <- read.table(header=TRUE,
colClasses=c("character","character","numeric"), text=txt)
d$CheckInDate <- as.Date(d$CheckInDate, as.Date, format="%d/%m/%Y")
isEndOfRun <- function(x) c(x[-1] != x[-length(x)], TRUE)
dSorted <- d[order(d$Name, d$CheckInDate), ]
dLatestVisit <- dSorted[isEndOfRun(dSorted$Name), ]
dLatestVisit
Name CheckInDate Temp
4 John 2014-04-01 99.0
2 Mary 2014-03-01 98.1
3 Sam 2014-04-01 97.5
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Fri, Jan 23, 2015 at 3:43 PM, Tan, Richard <r...@panagora.com> 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
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______________________________________________
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