Às 12:38 de 04/12/2024, Gerrit Eichner escreveu:
Dear list,
is anyone aware of the following behavious of diag when used to replace
diagonals (plural!) of a matrix?
Small example: The following is documented and clearly to be expected:
A <- matrix(0, nrow = 5, ncol = 5)
diag(A) <- 1; A
BUT, what about the following? When executing the code of `diag<-` line
by line, it throws errors. So why does it work?
diag(A[-1, ]) <- 2; A
diag(A[-5, -1]) <- 3; A
diag(A[-5, -(1:2)]) <- 4; A
Any ideas?
TIA and best regards -- Gerrit
---------------------------------------------------------------------
Dr. Gerrit Eichner Mathematical Institute, Room 215
gerrit.eich...@math.uni-giessen.de Justus-Liebig-University Giessen
Tel: +49-(0)641-99-32104 Arndtstr. 2, 35392 Giessen, Germany
https://www.uni-giessen.de/math/eichner
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Hello,
I cannot reproduce any error, everything works as expected.
sessionInfo at the end.
A <- matrix(0, nrow = 5, ncol = 5)
diag(A) <- 1; A
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 0 0 0 0
# [2,] 0 1 0 0 0
# [3,] 0 0 1 0 0
# [4,] 0 0 0 1 0
# [5,] 0 0 0 0 1
diag(A[-1, ]) <- 2; A
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 0 0 0 0
# [2,] 2 1 0 0 0
# [3,] 0 2 1 0 0
# [4,] 0 0 2 1 0
# [5,] 0 0 0 2 1
diag(A[-5, -1]) <- 3; A
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 3 0 0 0
# [2,] 2 1 3 0 0
# [3,] 0 2 1 3 0
# [4,] 0 0 2 1 3
# [5,] 0 0 0 2 1
diag(A[-5, -(1:2)]) <- 4; A
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 3 4 0 0
# [2,] 2 1 3 4 0
# [3,] 0 2 1 3 4
# [4,] 0 0 2 1 3
# [5,] 0 0 0 2 1
sessionInfo()
# R version 4.4.2 (2024-10-31 ucrt)
# Platform: x86_64-w64-mingw32/x64
# Running under: Windows 11 x64 (build 22631)
#
# Matrix products: default
#
#
# locale:
# [1] LC_COLLATE=Portuguese_Portugal.utf8
LC_CTYPE=Portuguese_Portugal.utf8
# [3] LC_MONETARY=Portuguese_Portugal.utf8 LC_NUMERIC=C
# [5] LC_TIME=Portuguese_Portugal.utf8
#
# time zone: Europe/Lisbon
# tzcode source: internal
#
# attached base packages:
# [1] stats graphics grDevices utils datasets methods base
#
# loaded via a namespace (and not attached):
# [1] compiler_4.4.2
#
Hope this helps,
Rui Barradas
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