Merge two matrix by column names and row names

Question

I want to join the two matrices by their column names and row names.

The elements in both matrices are numeric, and the merge value is to average the two matrices that have emerged together.

matrix1:

  A B C 

x 1 4 3

z 5 2 4

k 1 2 3

and matrix2:

  A B C D

x 6 4 1 2

y 2 3 1 3

z 1 4 1 4 

k 7 5 3 1

The output will be:

   A   B   C  D

x 3.5  4   2  2

y  2   3   1  3

z  3   3  2.5 4

k  4  3.5  3  1

My opinion is to use the for loop or apply function, but if the matrices are huge, then this program will run for a long time.

Answer 1

In R programming, you can use the rownames and colnames to subset matrix2 and update only part of it.

matrix2[rownames(matrix1), colnames(matrix1)] <- (matrix1 + matrix2[rownames(matrix1), colnames(matrix1)])/2

matrix2

#    A   B   C D

#x 3.5 4.0 2.0 2

#y 2.0 3.0 1.0 3

#z 3.0 3.0 2.5 4

#k 4.0 3.5 3.0 1

data

matrix1 <- structure(c(1L, 5L, 1L, 4L, 2L, 2L, 3L, 4L, 3L), .Dim = c(3L, 

           3L), .Dimnames = list(c("x", "z", "k"), c("A", "B", "C")))

matrix2 <- structure(c(6L, 2L, 1L, 7L, 4L, 3L, 4L, 5L, 1L, 1L, 1L, 3L, 2L, 

3L, 4L, 1L), .Dim = c(4L, 4L), .Dimnames = list(c("x", "y", "z", 

"k"), c("A", "B", "C", "D")))