R help - Jun 2009 - How do I get just the two last tokens of each string in a vector?

Dear list,

Sorry for asking this very silly question on the list, but I seem to
have made my life complicated by going into string manipulation in
vectors.
What I need is to get the last part of a sting (the two last tokens,
separated by a space), and of course, this should be done for all
strings in a vector, creating a new vector of exual size.

So,

a <- c(" %L H*L L*H H%", "%L H* H%",  "%L L*H
%",   "%L L*H %" )

should be made into a vector

 c(" L*H H%", "H* H%",  "L*H %",   "L*H
%" )

I have tried strsplit, but it seems to produce a structure I cannot
get to work in this context. Any ideas on how to solve this?

Thankful for all the help I can get.

/Fredrik


-- 
"Life is like a trumpet - if you don't put anything into it, you
don't
get anything out of it."

This should do it
> a <- c(" %L H*L L*H H%", "%L H* H%",  "%L L*H
%",   "%L L*H %" )
> # split the strings
> x <- strsplit(a, ' ')
> # get last two tokens
> sapply(x, function(.tokens) paste(tail(.tokens, 2), collapse=' '))
[1] "L*H H%" "H* H%"  "L*H %"  "L*H
%"
>
>

On Fri, Jun 26, 2009 at 7:21 AM, Fredrik Karlsson
<dargosch@gmail.com>wrote:
> Dear list,
>
> Sorry for asking this very silly question on the list, but I seem to
> have made my life complicated by going into string manipulation in
> vectors.
> What I need is to get the last part of a sting (the two last tokens,
> separated by a space), and of course, this should be done for all
> strings in a vector, creating a new vector of exual size.
>
> So,
>
> a <- c(" %L H*L L*H H%", "%L H* H%",  "%L L*H
%",   "%L L*H %" )
>
> should be made into a vector
>
>  c(" L*H H%", "H* H%",  "L*H %",   "L*H
%" )
>
> I have tried strsplit, but it seems to produce a structure I cannot
> get to work in this context. Any ideas on how to solve this?
>
> Thankful for all the help I can get.
>
> /Fredrik
>
>
> --
> "Life is like a trumpet - if you don't put anything into it, you
don't
> get anything out of it."
>
> ______________________________________________
> R-help@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<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 that you are trying to solve?

	[[alternative HTML version deleted]]

I have the feeling that this is a very clumsy way to do it but I think it does
what you want.
================================================================a <- c("
%L H*L L*H H%", "%L H* H%",  "%L L*H %",   "%L L*H
%" )
mylist <- strsplit(a," ")
pick <- function(x) {tail(x,2) }
unlist(pick(mylist)

================================================================

--- On Fri, 6/26/09, Fredrik Karlsson <dargosch at gmail.com> wrote:
> From: Fredrik Karlsson <dargosch at gmail.com>
> Subject: [R] How do I get just the two last tokens of each string in a
vector?
> To: "R-Help List" <r-help at stat.math.ethz.ch>
> Received: Friday, June 26, 2009, 7:21 AM
> Dear list,
> 
> Sorry for asking this very silly question on the list, but
> I seem to
> have made my life complicated by going into string
> manipulation in
> vectors.
> What I need is to get the last part of a sting (the two
> last tokens,
> separated by a space), and of course, this should be done
> for all
> strings in a vector, creating a new vector of exual size.
> 
> So,
> 
> a <- c(" %L H*L L*H H%", "%L H* H%",? "%L L*H
> %",???"%L L*H %" )
> 
> should be made into a vector
> 
>  c(" L*H H%", "H* H%",? "L*H %",???"L*H
> %" )
> 
> I have tried strsplit, but it seems to produce a structure
> I cannot
> get to work in this context. Any ideas on how to solve
> this?
> 
> Thankful for all the help I can get.
> 
> /Fredrik
> 
> 
> -- 
> "Life is like a trumpet - if you don't put anything into
> it, you don't
> get anything out of it."
> 
> ______________________________________________
> 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.
> 

      __________________________________________________________________
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One way is:

a <- c(" %L H*L L*H H%", "%L H* H%",  "%L L*H
%",   "%L L*H %" )
> sub("^.*(^| )([^ ]+ [^ ]+$)","\\2",a)
[1] "L*H H%" "H* H%"  "L*H %"  "L*H %"

Just be aware that this is not terribly efficient for very large strings.

            -s

On Fri, Jun 26, 2009 at 7:21 AM, Fredrik Karlsson<dargosch at gmail.com>
wrote:
> Dear list,
>
> Sorry for asking this very silly question on the list, but I seem to
> have made my life complicated by going into string manipulation in
> vectors.
> What I need is to get the last part of a sting (the two last tokens,
> separated by a space), and of course, this should be done for all
> strings in a vector, creating a new vector of exual size.
>
> So,
>
> a <- c(" %L H*L L*H H%", "%L H* H%", ?"%L L*H
%", ? "%L L*H %" )
>
> should be made into a vector
>
> ?c(" L*H H%", "H* H%", ?"L*H %", ? "L*H
%" )
>
> I have tried strsplit, but it seems to produce a structure I cannot
> get to work in this context. Any ideas on how to solve this?
>
> Thankful for all the help I can get.
>
> /Fredrik
>
>
> --
> "Life is like a trumpet - if you don't put anything into it, you
don't
> get anything out of it."
>
> ______________________________________________
> 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.
>

Here is a similar solution using strapply in gsubfn.
The pattern matches non-spaces, [^ ]+, followed by a space
followed by non-spaces followed by end-of-string, $.
> library(gsubfn)
> strapply(a, "[^ ]+ [^ ]+$", simplify = c)
[1] "L*H H%" "H* H%"  "L*H %"  "L*H %"


On Fri, Jun 26, 2009 at 7:21 AM, Fredrik Karlsson<dargosch at gmail.com>
wrote:
> Dear list,
>
> Sorry for asking this very silly question on the list, but I seem to
> have made my life complicated by going into string manipulation in
> vectors.
> What I need is to get the last part of a sting (the two last tokens,
> separated by a space), and of course, this should be done for all
> strings in a vector, creating a new vector of exual size.
>
> So,
>
> a <- c(" %L H*L L*H H%", "%L H* H%", ?"%L L*H
%", ? "%L L*H %" )
>
> should be made into a vector
>
> ?c(" L*H H%", "H* H%", ?"L*H %", ? "L*H
%" )
>
> I have tried strsplit, but it seems to produce a structure I cannot
> get to work in this context. Any ideas on how to solve this?
>
> Thankful for all the help I can get.
>
> /Fredrik
>
>
> --
> "Life is like a trumpet - if you don't put anything into it, you
don't
> get anything out of it."
>
> ______________________________________________
> 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.
>