[Rd] Inconsistency with matrix indexing (PR#8214)
stefan.albrecht@allianz.com
stefan.albrecht at allianz.com
Tue Oct 18 14:21:41 CEST 2005
Full_Name: Stefan Albrecht
Version: 2.2.0
OS: Windows XP
Submission from: (NULL) (194.127.2.74)
Dear all,
in the new R 2.2.0, the matrix indexing has been changed. In my opinion, this
leads to an inconsistency when indexing one-row matrices.
Take
> (mat <- matrix(1:9, nrow = 3, dimnames = list(paste("r", 1:3, sep = ""),
paste("c", 1:3, sep = ""))))
c1 c2 c3
r1 1 4 7
r2 2 5 8
r3 3 6 9
Now taking the first row of the first-row of mat preserves the column names
> mat[1, , drop = FALSE][1, ]
c1 c2 c3
1 4 7
This is not true for the first column of the first-row of mat
> mat[1, , drop = FALSE][, 1]
[1] 1
However, for the first column of the first two rows of mat the row names are
retained
> mat[1:2, , drop = FALSE][, 1]
r1 r2
1 2
This feature can lead to problems when indexing matrixes of different row
numbers, since the row names are not preserved in all cases.
I suggest to preseve the row names also for
> mat[1, , drop = FALSE][, 1]
Would it be possible to implement this feature? Many thanks.
With best regards,
Stefan Albrecht
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