[R] The assign(paste(...,i),...) idiom

[Bert Gunter]

Perhaps a good R WIKI topic, though there's no assurance that info there
would be consulted, of course... 


Bert Gunter
Genentech Nonclinical Biostatistics
650-467-7374

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of baptiste auguie
Sent: Monday, April 20, 2009 3:07 PM
To: Stavros Macrakis
Cc: r-help
Subject: Re: [R] The assign(paste(...,i),...) idiom

I vaguely recall thinking with such convoluted constructs when  
switching from Matlab to R. The lack of generic data structures such  
as lists makes you define variable names that you can identify and  
manipulate. There are structures in Matlab, but I think they are much  
less used than lists in R.

I was wondering earlier how to help newcomers understand the  
limitations of this strange and unnecessary construct without going  
through the details of each particular example that comes up in the r- 
help list. Perhaps a simple generic and illustrative example in the R  
wiki? (say, (i) list some data files in a directory, (ii)load into  
data.frames, (iii)manipulate some columns, (iv)store in a list,  
(v)manipulate the list, (vi)plot some results).

Now, how would we go about naming that entry...? Perhaps 'A beginner's  
assignment'


baptiste


On 20 Apr 2009, at 22:44, Stavros Macrakis wrote:

> Judging from the traffic on this mailing list, a lot of R beginners
> are trying to write things like
>
>      assign( paste( "myvar", i), ...)
>
> where they really should probably be writing
>
>      myvar[i] <- ...
>
> Do we have any idea where this bizarre habit comes from?
>
>          -s
>
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_____________________________

Baptiste Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag

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