[Rd] '==' operator: inconsistency in data.frame(...) == NULL

[Hilmar Berger]

Sorry, I can't reproduce the example below even on the same machine. 
However, the following example produces the same error as NULL values in 
prior examples:

 > setClass("FOOCLASS",
+          representation("list")
+ )
 > ma = new("FOOCLASS", list(M=matrix(rnorm(300), 30,10)))
 > isS4(ma)
[1] TRUE
 > data.frame(a=1:3) == ma
Error in matrix(unlist(value, recursive = FALSE, use.names = FALSE), 
nrow = nr,  :
   length of 'dimnames' [2] not equal to array extent

Best,
Hilmar


On 11/09/2019 12:24, Hilmar Berger wrote:
> Another example where a data.frame is compared to (here non-null, 
> non-empty) non-atomic values in Ops.data.frame, resulting in an error 
> message:
>
> setClass("FOOCLASS2",
>          slots = c(M="matrix")
> )
> ma = new("FOOCLASS2", M=matrix(rnorm(300), 30,10))
>
> > isS4(ma)
> [1] TRUE
> > ma == data.frame(a=1:3)
> Error in eval(f) : dims [product 1] do not match the length of object [3]
>
> As for the NULL/logical(0) cases I would suggest to explicitly test 
> for invalid conditions in Ops.data.frame and generate a comprehensible 
> message (e.g. "comparison is possible only for atomic and list types") 
> if appropriate.
>
> Best regards,
> Hilmar
>
>
> On 11/09/2019 11:55, Hilmar Berger wrote:
>>
>> In the data.frame()==NULL cases I have the impression that the fact 
>> that both sides are non-atomic is not properly detected and therefore 
>> R tries to go on with the == method for data.frames.
>>
>> From a cursory check in Ops.data.frame() and some debugging I have 
>> the impression that the case of the second argument being non-atomic 
>> or empty is not handled at all and the function progresses until the 
>> end, where it fails in the last step on an empty value:
>>
>> matrix(unlist(value, recursive = FALSE, use.names = FALSE),
>>     nrow = nr, dimnames = list(rn, cn)) 
>

-- 
Dr. Hilmar Berger, MD
Max Planck Institute for Infection Biology
Charitéplatz 1
D-10117 Berlin
GERMANY

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