R help - Jun 2006 - Access and assign list sub-elements using a string such as "l$a$b"

If I have a list I can set a sub-element as follows on the command line:

people=list()
people$tom$hair="brown"
people

But what if I have a string containing the name of the sub-element that I
want to access?

subel= "people$tom$hair"

get(subel) # returns error
assign(subel,"red") # silent but doesn't change list
people

The attempts above using assign/get won't do what I am trying to do [nor
according to the help should they].  I would be very grateful for any
suggestions.  Many thanks,

Greg.

-- 
Gregory Jefferis, PhD                                   and:
Research Fellow    
Department of Zoology                                   St John's College
University of Cambridge                                 Cambridge
Downing Street                                          CB2 1TP
Cambridge, CB2 3EJ 
United Kingdom

Lab Tel: +44 (0)1223 336683                     Office: +44 (0)1223 339899
Lab Fax: +44 (0)1223 336676

http://www.zoo.cam.ac.uk/zoostaff/jefferis.html           gsxej2 at cam.ac.uk

Hi
very, very close


On 15 Jun 2006 at 13:27, Gregory Jefferis wrote:

Date sent:      	Thu, 15 Jun 2006 13:27:05 +0100
From:           	Gregory Jefferis <gsxej2 at cam.ac.uk>
To:             	"r-help-request at stat.math.ethz.ch"
<r-help-request at stat.math.ethz.ch>
Forwarded to:   	<r-help at stat.math.ethz.ch>
Forwarded by:   	Gregory Jefferis <gsxej2 at cam.ac.uk>
Date forwarded: 	Thu, 15 Jun 2006 14:54:13 +0100
Subject:        	[R] Access and assign list sub-elements using a string such as
	"l$a$b"
> If I have a list I can set a sub-element as follows on the command
> line:
> 
> people=list()
> people$tom$hair="brown"
> people
> 
> But what if I have a string containing the name of the sub-element
> that I want to access?
> 
> subel= "people$tom$hair"
> 
> get(subel) # returns error
> assign(subel,"red") # silent but doesn't change list
> people
See what happens when

people<-assign(subel, "red")

HTH
Petr

> 
> The attempts above using assign/get won't do what I am trying to do
> [nor according to the help should they].  I would be very grateful for
> any suggestions.  Many thanks,
> 
> Greg.
> 
> -- 
> Gregory Jefferis, PhD                                   and:
> Research Fellow    
> Department of Zoology                                   St John's
> College University of Cambridge                                
> Cambridge Downing Street                                   CB2 1TP
> Cambridge, CB2 3EJ United Kingdom
> 
> Lab Tel: +44 (0)1223 336683                     Office: +44 (0)1223
> 339899 Lab Fax: +44 (0)1223 336676
> 
> http://www.zoo.cam.ac.uk/zoostaff/jefferis.html          
> gsxej2 at cam.ac.uk
> 
> ______________________________________________
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Petr Pikal
petr.pikal at precheza.cz