How can I find the row and column of a matrix having the closest value to its mean? in R

Question

I have a large matrix, like this one:

NCols=100
NRows=100

myMat<-matrix(runif(NCols*NRows), ncol=NCols)

I am interested in locating which row and column have the closest value to the mean or median of all values of the matrix, calculated as mean(myMat).

How could I do this in R?

Answer 1

Try this:

set.seed(45) # just for reproducibility
NCols <- 100
NRows <- 100
myMat <- matrix(runif(NCols*NRows), ncol=NCols)

mat_minus_mean <- abs(myMat - mean(myMat))
idx <- which(mat_minus_mean == min(mat_minus_mean), arr.ind = TRUE)
#      row col
# [1,]   5  33

> myMat[idx]
# [1] 0.5012305 # mean(myMat) is 0.5012474