R help - Feb 2008 - Converting a character string into an object variable

R-helpers:

 Assume that I want to create a series of sequentially named R objects.  For
example, I might want to call these objects V1, V2, V3 ... V50.  To do this,
I thought of some sort of looping function like:

 input.value <- seq(1:50) * 3
for(i in 1:50){
   paste("V", i, sep="") <- input.value[i]
}


 Of course this loop will not work since the paste function returns a
character string that cannot be a variable.  How can I construct a loop to
create sequential variables and assign a value to them in the same spirit of
the loop above?

 Brant Inman
Mayo Clinic

	[[alternative HTML version deleted]]

assign(paste("V", i, sep=""), input.value[i])

b

On Jan 31, 2008, at 11:28 PM, Brant Inman wrote:
> R-helpers:
>
> Assume that I want to create a series of sequentially named R  
> objects.  For
> example, I might want to call these objects V1, V2, V3 ... V50.  To  
> do this,
> I thought of some sort of looping function like:
>
> input.value <- seq(1:50) * 3
> for(i in 1:50){
>   paste("V", i, sep="") <- input.value[i]
> }
>
>
> Of course this loop will not work since the paste function returns a
> character string that cannot be a variable.  How can I construct a  
> loop to
> create sequential variables and assign a value to them in the same  
> spirit of
> the loop above?
>
> Brant Inman
> Mayo Clinic
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.

You mean the list has elements called "V1"  ... "V50"?

assign(paste("output", i, sep=""),
mylist[[paste("V", i, sep="")]])

b

On Jan 31, 2008, at 11:44 PM, "Inman, Brant A., M.D." <Inman.Brant
at mayo.edu
 > wrote:
> Thanks B.
>
> Now what if V1, V2, V3 ...V50 are elements of a list and I wanted to
> extract them?  For example:
>
> output1 <- mylist[[V1]]
> output2 <- mylist[[V2]]
> ...
> output50 <- mylist[[V50]]
>
>
> Brant
> -----Original Message-----
> From: brant.inman+caf_=inman.brant=mayo.edu at gmail.com
> [mailto:brant.inman+caf_=inman.brant=mayo.edu at gmail.com] On Behalf Of
> Benilton Carvalho
> Sent: Thursday, January 31, 2008 10:35 PM
> To: Brant Inman
> Cc: r-help at r-project.org
> Subject: Re: [R] Converting a character string into an object variable
>
> assign(paste("V", i, sep=""), input.value[i])
>
> b
>
> On Jan 31, 2008, at 11:28 PM, Brant Inman wrote:
>
>> R-helpers:
>>
>> Assume that I want to create a series of sequentially named R
>> objects.  For
>> example, I might want to call these objects V1, V2, V3 ... V50.  To
>> do this,
>> I thought of some sort of looping function like:
>>
>> input.value <- seq(1:50) * 3
>> for(i in 1:50){
>>  paste("V", i, sep="") <- input.value[i]
>> }
>>
>>
>> Of course this loop will not work since the paste function returns a
>> character string that cannot be a variable.  How can I construct a
>> loop to
>> create sequential variables and assign a value to them in the same
>> spirit of
>> the loop above?
>>
>> Brant Inman
>> Mayo Clinic
>>
>>    [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.

This is pretty standard.  Here are two solutions, there are many more.

input.value <- 3*(1:50)
for(i in 1:50) 
	assign(paste("V", i, sep = ""), input.value[i])

---
input.value <- 3*(1:50)
for(i in 1:50) eval(substitute(

	V <- input.value[i], 
		
	list(V = as.name(paste("V", i, sep = "")))))
---

The second is more obscure, but points to a more general way of doing
things.  I hope!

Bill Venables.



-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Brant Inman
Sent: Friday, 1 February 2008 2:29 PM
To: r-help at r-project.org
Subject: [R] Converting a character string into an object variable

R-helpers:

 Assume that I want to create a series of sequentially named R objects.
For
example, I might want to call these objects V1, V2, V3 ... V50.  To do
this,
I thought of some sort of looping function like:

 input.value <- seq(1:50) * 3
for(i in 1:50){
   paste("V", i, sep="") <- input.value[i]
}


 Of course this loop will not work since the paste function returns a
character string that cannot be a variable.  How can I construct a loop
to
create sequential variables and assign a value to them in the same
spirit of
the loop above?

 Brant Inman
Mayo Clinic

	[[alternative HTML version deleted]]

______________________________________________
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.