Message-ID: <912227ef-441e-b5f6-8ed7-6af6164f17b5@sapo.pt>
Date: 2021-03-03T11:12:57Z
From: Rui Barradas
Subject: Column-by-column division
In-Reply-To: <97051aa1-865c-6a8c-cf75-947a2cb8e34e@ntu.edu.tw>
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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