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

[Peter Dalgaard]

Cliff Behrens wrote:
> Peter,
> 
> OK...here is reproducible, self-contained code:
> 
> library(gregmisc)

Relying on a 3rd party package is not kosher either... Whatever did
list("NA"=2)  or l <- list(2); names(l) <- "NA" do to you?

> 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:

Anyways....  As I thought:

Remember that NA is a reserved word. You get the same kind of reaction 
if you name an element "for" or "in". It denotes that you need to quote 
the name for indexing with $:

 > names(l) <- "NA"
 > l$NA
Error: unexpected numeric constant in "l$NA"
 > l$`NA`
[1] 2
 > l$"NA"
[1] 2
 > l[["NA"]]
[1] 2
 > names(l)
[1] "NA"

> ......
> 
> $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
>>  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
>> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907
> 


-- 
    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907