R help - Jan 2013 - How to extract elements from vector in reverse order?

Hi all mailing listers,

I wanna get the last several elments of vector.
 e.g.  x <- c(1,2,3,.....,78, 79, 80)

How can I implement to assign last three elements to y,  y <- c(78, 79, 80)
?

In Matlab, It can easily achieve by y=x(end-2:end)


Thanks

Huaping Wan

	[[alternative HTML version deleted]]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of hp wan
> Sent: Thursday, January 24, 2013 4:23 PM
> To: r-help at r-project.org
> Subject: [R] How to extract elements from vector in reverse order?
> 
> Hi all mailing listers,
> 
> I wanna get the last several elments of vector.
>  e.g.  x <- c(1,2,3,.....,78, 79, 80)
> 
> How can I implement to assign last three elements to y,  y <- c(78, 79,
> 80)
> ?
> 
> In Matlab, It can easily achieve by y=x(end-2:end)
> 
> 
> Thanks
> 
> Huaping Wan
> 
You can get what you want in much the same way

y <- x[(length(x)-2):length(x)]


Hope this is helpful,

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204

On Jan 24, 2013, at 4:23 PM, hp wan wrote:
> Hi all mailing listers,
> 
> I wanna get the last several elments of vector.
> e.g.  x <- c(1,2,3,.....,78, 79, 80)
> 
> How can I implement to assign last three elements to y,  y <- c(78, 79,
80)
> ?
?tail
> In Matlab, It can easily achieve by y=x(end-2:end)
y <- tail(x, 3)

-- 
David Winsemius
Alameda, CA, USA

Hi,
?x<-1:80
y<- x[-(1:77)]
y

#[1] 78 79 80
#or 

?tail() #already suggested

If you want only the last element,,
library(pastecs)
last(x)
#[1] 80
A.K.




----- Original Message -----
From: hp wan <huaping.wan at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Thursday, January 24, 2013 7:23 PM
Subject: [R] How to extract elements from vector in reverse order?

Hi all mailing listers,

I wanna get the last several elments of vector.
e.g.? x <- c(1,2,3,.....,78, 79, 80)

How can I implement to assign last three elements to y,? y <- c(78, 79, 80)
?

In Matlab, It can easily achieve by y=x(end-2:end)


Thanks

Huaping Wan

??? [[alternative HTML version deleted]]

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