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Does a subset array with NULL not reduce size?

I wonder if there could be some reason for this default behavior? If there are any agreed upon quirks that I would love to know about.

Below are two different queries (resulting in a length of 20 and 0), but I expect that they will have the same behavior regarding removing redundant measurements. The subset, NULLfor some reason, preserves an empty dimension. ?drop:

Delete array sizes that have only one level.

What is the save point of 0 level measurements with drop=TRUE?

I am developing a class similar to an array, and because of this I hit inconsistency with base::array. Should I report such a problem on the R dev platform?

set.seed(1L)
ar.dimnames = list(color = sort(c("green","yellow","red")), 
                   year = as.character(2011:2015), 
                   status = sort(c("active","inactive","archived","removed")))
ar.dim = sapply(ar.dimnames, length)
ar = array(sample(c(rep(NA, 4), 4:7/2), prod(ar.dim), TRUE), 
           unname(ar.dim),
           ar.dimnames)
r1 = ar["green",,,drop=TRUE]
dimnames(r1)
#$year
#[1] "2011" "2012" "2013" "2014" "2015"
#
#$status
#[1] "active"   "archived" "inactive" "removed" 
#
length(r1)
#[1] 20
r2 = ar[NULL,,,drop=TRUE]
dimnames(r2)
#$color
#NULL
#
#$year
#[1] "2011" "2012" "2013" "2014" "2015"
#
#$status
#[1] "active"   "archived" "inactive" "removed" 
#
length(r2)
#[1] 0
+4
1

, drop = FALSE , , 1 , - 0 . , . , , . , r2 - NO-. , , , . : , , 1 * 5 * 4 = 5 * 4, 0 , 0 * 5 * 4 = 0, 5 * 4.

:

  • , , . 0 , , (0) .

  • 0 , NULL NO-. (1 ), . , dropping 0 (, , 0 , , , dimnames).

  • , R dev.

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