R: Examples for 'matrixStats::indexByRow'

### ** Examples

dim <- c(5, 4)
X <- matrix(NA_integer_, nrow = dim[1], ncol = dim[2])
Y <- t(X)
idxs <- seq_along(X)

# Assign by columns
X[idxs] <- idxs
print(X)

     [,1] [,2] [,3] [,4]
[1,]    1    6   11   16
[2,]    2    7   12   17
[3,]    3    8   13   18
[4,]    4    9   14   19
[5,]    5   10   15   20

# Assign by rows
Y[indexByRow(dim(Y), idxs)] <- idxs
print(Y)

     [,1] [,2] [,3] [,4] [,5]
[1,]    1    2    3    4    5
[2,]    6    7    8    9   10
[3,]   11   12   13   14   15
[4,]   16   17   18   19   20

stopifnot(X == t(Y))

Examples for 'matrixStats::indexByRow'

Translates matrix indices by rows into indices by columns