[R] mget empty strings

Liaw, Andy andy_liaw at merck.com
Thu May 12 16:04:14 CEST 2005


Here's one way to work around it:

> nm <- c("x", "", "y")
> x <- 10; y <- 20
> myObj <- structure(vector(mode="list", length=length(nm)), names=nm)
> goodNames <- nm[nchar(nm) > 0]
> myObj[goodNames] <- mget(goodNames, .GlobalEnv)
> myObj
$x
[1] 10

[[2]]
NULL

$y
[1] 20

Andy

> From: Georg Otto
> 
> Dear R community,
> 
> I am a beginner to R and have a question concerning mget, 
> about I could 
> not find anything in the various documentation.
> 
> I have a column in a dataframe x for which I want to get values in y:
> 
> mget(x[,1], env=y, ifnotfound=NA)
> 
> I receive an error mesage:
> 
> Error in mget(x[, 1], env = y, ifnotfound = NA) :
>          attempt to use zero-length variable name
> 
> this is probably due to the fact that some of the values in x[,1] are 
> empty ("")
> 
> I would like to get a "NA" for these values, and the found value for 
> those where mget finds one. Could anyone tell me how this is done 
> efficiently?
> 
> Thanks a lot in advance!
> 
> Georg
> 
> 
> P.S. I am in digest mode, cc'ing the answer directly to me 
> would be nice
> 
> 
> -- 
> Georg Wilhelm Otto
> Max-Planck-Institute for Developmental Biology
> Spemannstrasse 35/III
> D-72076 Tuebingen Germany
> phone: +49-7071-601 401
> http://www.eb.tuebingen.mpg.de
> 
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