I have a 10 x 2 matrix x. Like to divide the first column by s[1] and second column by s[2]. The following lines work but are clumsy. Any idea? Thanks. > x ????? [,1] [,2] ?[1,]??? 1?? 11 ?[2,]??? 2?? 12 ?[3,]??? 3?? 13 ?[4,]??? 4?? 14 ?[5,]??? 5?? 15 ?[6,]??? 6?? 16 ?[7,]??? 7?? 17 ?[8,]??? 8?? 18 ?[9,]??? 9?? 19 [10,]?? 10?? 20 > s [1] 1 2 > t(t(x)/s) ????? [,1] [,2] ?[1,]??? 1? 5.5 ?[2,]??? 2? 6.0 ?[3,]??? 3? 6.5 ?[4,]??? 4? 7.0 ?[5,]??? 5? 7.5 ?[6,]??? 6? 8.0 ?[7,]??? 7? 8.5 ?[8,]??? 8? 9.0 ?[9,]??? 9? 9.5 [10,]?? 10 10.0
Hello,
Maybe define an infix operator?
`%!%` <- function(x, y) {
stopifnot(ncol(x) == length(y))
t(t(x)/y)
}
x <- matrix(1:20, ncol = 2)
s <- 1:2
x %!% s
x %!% 1:4
Hope this helps,
Rui Barradas
?s 11:00 de 03/03/21, Steven Yen escreveu:> I have a 10 x 2 matrix x. Like to divide the first column by s[1] and
> second column by s[2]. The following lines work but are clumsy. Any
> idea? Thanks.
>
> > x
> ????? [,1] [,2]
> ?[1,]??? 1?? 11
> ?[2,]??? 2?? 12
> ?[3,]??? 3?? 13
> ?[4,]??? 4?? 14
> ?[5,]??? 5?? 15
> ?[6,]??? 6?? 16
> ?[7,]??? 7?? 17
> ?[8,]??? 8?? 18
> ?[9,]??? 9?? 19
> [10,]?? 10?? 20
> > s
> [1] 1 2
> > t(t(x)/s)
> ????? [,1] [,2]
> ?[1,]??? 1? 5.5
> ?[2,]??? 2? 6.0
> ?[3,]??? 3? 6.5
> ?[4,]??? 4? 7.0
> ?[5,]??? 5? 7.5
> ?[6,]??? 6? 8.0
> ?[7,]??? 7? 8.5
> ?[8,]??? 8? 9.0
> ?[9,]??? 9? 9.5
> [10,]?? 10 10.0
>
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To make sure the scalar is used instead of using the recycled vector s, maybe like this x <- matrix(1:20, nrow=10) s <- c(1,2) sapply(1:2, function(i) x[,i]/s[i]) -----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Steven Yen Sent: Wednesday, March 3, 2021 6:00 AM To: R-help Mailing List <r-help at r-project.org> Subject: [R] Column-by-column division I have a 10 x 2 matrix x. Like to divide the first column by s[1] and second column by s[2]. The following lines work but are clumsy. Any idea? Thanks. > x ????? [,1] [,2] ?[1,]??? 1?? 11 ?[2,]??? 2?? 12 ?[3,]??? 3?? 13 ?[4,]??? 4?? 14 ?[5,]??? 5?? 15 ?[6,]??? 6?? 16 ?[7,]??? 7?? 17 ?[8,]??? 8?? 18 ?[9,]??? 9?? 19 [10,]?? 10?? 20 > s [1] 1 2 > t(t(x)/s) ????? [,1] [,2] ?[1,]??? 1? 5.5 ?[2,]??? 2? 6.0 ?[3,]??? 3? 6.5 ?[4,]??? 4? 7.0 ?[5,]??? 5? 7.5 ?[6,]??? 6? 8.0 ?[7,]??? 7? 8.5 ?[8,]??? 8? 9.0 ?[9,]??? 9? 9.5 [10,]?? 10 10.0 ______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.