Set row names of matrices in an array

Question

I have an array consisting many 2*3 matrices.

I want to give same row names to both rows of each matrix in my array. I'm trying dimnames(), however I'm not getting what I want.

c1a <- c("1a","1a","1a")
c1b <- c("1b","1b","1b")
c2a <- c("2a","2a","2a")
c2b <- c("2b","2b","2b")
c3a <- c("3a","3a","3a")
c3b <- c("3b","3b","3b")
df1 <- as.data.frame(rbind(c1a,c2a,c3a))
df2 <- as.data.frame(rbind(c1b,c2b,c3b))

my.arr <- simplify2array(unname(Map(rbind, asplit(df1, 1), asplit(df2, 
1))))

dimnames(Y)[[1]] <- c("a", "b")

Please include reproducible sample data (e.g. using `dput`). It's not clear to me what you're trying to do. — Maurits Evers, Aug 16 '21 at 12:26

akrun · Answer 1 · 2021-08-16T23:16:15.163

3

We could just do this with dimnames. There is no need for any looping

dimnames(my.arr)[[1]] <- c('a', 'b')

-output

> my.arr
, , 1

  V1   V2   V3  
a "1a" "1a" "1a"
b "1b" "1b" "1b"

, , 2

  V1   V2   V3  
a "2a" "2a" "2a"
b "2b" "2b" "2b"

, , 3

  V1   V2   V3  
a "3a" "3a" "3a"
b "3b" "3b" "3b"

edited Aug 16 '21 at 23:16

answered Aug 16 '21 at 17:01

akrun

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score 2 · Answer 2 · answered Aug 16 '21 at 12:45

Use apply over 3rd dimension -

apply(my.arr, 3, function(x) {rownames(x) <- c('a', 'b');x}, simplify = FALSE)

#[[1]]
#   V1   V2   V3  
#a "1a" "1a" "1a"
#b "1b" "1b" "1b"

#[[2]]
#   V1   V2   V3  
#a "2a" "2a" "2a"
#b "2b" "2b" "2b"

#[[3]]
#   V1   V2   V3  
#a "3a" "3a" "3a"
#b "3b" "3b" "3b"

Set row names of matrices in an array

2 Answers2