Let's simplify this to consider a single vector, such as
x <- c(1,1,1,2,2,3,3,3,3,4,5,5,5)
in which equal elements are in contiguous blocks.
> diff(x)
[1] 0 0 1 0 1 0 0 0 1 1 0 0
Of course, there could be gaps, or the sequence might be descending
instead of ascending. So
> diff(x) != 0
We are
-help
Subject: Re: [R] how to find "first" or "last" record after sort in R
I prefer the duplicated() function, since the final code will be clear to a
future reader.
(Particularly when I am that future reader).
last <- !duplicated(mydata$ID, fromLast=TRUE) # point
Thanks Therneau, duplicated() function works well. --- Kai
On Friday, September 10, 2021, 05:13:47 AM PDT, Therneau, Terry M., Ph.D.
wrote:
I prefer the duplicated() function, since the final code will be clear to a
future reader.
(Particularly when I am that future reader).
last
I prefer the duplicated() function, since the final code will be clear to a future reader.
(Particularly when I am that future reader).
last <- !duplicated(mydata$ID, fromLast=TRUE) # point to the last ID for each
subject
mydata$data3[last] <- NA
Terry T.
(I read the list once a day in
then applying some functionality to each smaller data.frame to get
the result then recombining it back.
-Original Message-
From: R-help On Behalf Of Kai Yang via R-help
Sent: Thursday, September 9, 2021 3:00 PM
To: R-help Mailing List
Subject: [R] how to find "first" or "
Sorry, that should be
> id <- c(1,2,2,2,3,4,5,5)
> last.index <- cumsum(rle(id)$lengths)
> last.index
[1] 1 4 5 6 8
of course.
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom
Many ways to do this, of course, but if I understand correctly ?rle
may be the simplest, because you already have the data sorted by ID.
The following little example should give you the idea. It gets the
index of the last row in each id,, which you can then use to assign
NA's or whatever:
> id
Hello List,
Please look at the sample data frame below:
ID date1 date2 date3
1 2015-10-08 2015-12-17 2015-07-23
2 2016-01-16 NA 2015-10-08
3 2016-08-01 NA 2017-01-10
3 2017-01-10 NA
8 matches
Mail list logo
