On 2020-06-10 18:01 -0700, Jeff Newmiller wrote: > On June 10, 2020 5:29:10 PM PDT, Jinsong Zhao wrote: > > > > (3,1), (5,1), (5,2), (4,2), (4,3), (1,3), (1,2), (3,2) > > M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE) > ix <- expand.grid( r = seq.int( nrow( M ) ) > , c = seq.int( ncol( M ) ) > ) > ix[ 1 == c(M), ]
Dear Jinsong and Jeff,
I thought out this, really similar to Jeff's answer:
M <- matrix(c(2, 2, rep(1, 12), 2),
nrow=5, byrow=FALSE)
points <- expand.grid(1:nrow(M), 1:ncol(M))
points <- apply(points, 1, paste, collapse=",")
points <- matrix(paste0("(", points, ")"),
nrow=nrow(M))
paste(points[M==1], collapse=", ")
you get
[1] "(3,1), (4,1), (5,1), (1,2), (2,2), (3,2), (4,2), (5,2), (1,3),
(2,3), (3,3), (4,3)"
Best,
Rasmus
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