[R] Problem assigning "NA" as a level name in a list

[Cliff Behrens]

Peter,

OK...here is reproducible, self-contained code:

library(gregmisc)
columnNames <- c("A","B","C","D","N","a","b","c")
namePerms<- permutations(length(columnNames),2,columnNames,repeats=TRUE)
nameList <- paste(namePerms[,1],namePerms[,2],sep="")
dataList <- lapply(1:length(nameList), function(level) {})
names(dataList)<-  nameList  ## The "NA" is interpreted that the name is 
missing for one list in dataList

If you inspect the contents of dataList, you will find the following 
showing that the name "NA" is treated differently:

......

$Na
NULL

$`NA`
NULL

$Nb
NULL
.........
Peter Dalgaard wrote:
> Cliff Behrens wrote:
>> I want to generate a list (called "dataList" below) where each of its 
>> levels is named.  These names are assigned to nameList, which 
>> contains all possible permutations of size two taking letters from a 
>> larger alphabet, e.g., "aa",...,"Fd",..,"Z1",...  One of these 
>> permutations is the character string "NA".  It seems that when I try 
>> to name one of the dataList levels "NA", using names(dataList)<- 
>> nameList, the names() function assigns the missing character to the 
>> level.  Is there someway to preserve "NA" as the name of a level in 
>> dataList?  Here is the R code I have been using to do this.
>>
>> namePerms<- permutations(ncol(coinMat),2,colnames(coinMat),repeats=TRUE)
>> nameList <- paste(namePerms[,1],namePerms[,2],sep="")
>> dataList <- lapply(1:length(nameList), function(level) {})
>> names(dataList)<-  nameList     ## The "NA" in nameList is 
>> interpreted so that the name "NA" is missing for one level in dataList
>>
>> I am running R 2.4.1 in the Windows XP environment.
>>
>> Thanks for any help that can be offerred.
>
> Your example is not reproducible and self-contained. What is 
> "permutations" and "coinMat"??
>
> I bet it isn't minimal either.
>
> It doesn't seem to be happening for me with a recent(!) version of R, 
> but you could just be misinterpreting the backtick quoting.
>
> -
>    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
>   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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