matrix() fills by column unless byrow = TRUE.

Goal

Print a 2-by-3 units matrix.

m <- matrix(c(12, 8, 5, 4, 3, 2), nrow = 2, byrow = TRUE)
print(m)
print(dim(m))

m <- matrix(1:6, nrow = 3)
print(m[1, 2])

m <- matrix(c(12, 8, 5, 4), nrow = 2, dimnames = list(c("Nairobi", "Kisumu"), c("am", "pm")))
print(m)

print(rowSums(matrix(c(12, 8, 5, 4), nrow = 2, byrow = TRUE)))