**Copy and paste the following code to your R Studio platform or R version:**

# Matrices in R

?matrix

mat1 <- matrix(c(10, 9, 8, 7, 6, 5), nrow = 3, ncol = 2, byrow = TRUE)

# apparently the number of elements in the vector should be equal to the

# number we obtain when we multiply the nrow with the ncol number

print(mat1)

View(mat1)

# Accessing the matrix elements

mat1[2,2] # row, column in the matrix

mat1[3,1]

mat1[2, c(1,2)] # go to the second row and print the elements 1 and 2

mat2 <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 3, ncol = 2, byrow = FALSE)

mat2

mat3 <- matrix(c(1:9), nrow = 3, ncol = 3, byrow = TRUE)

mat3

mat3[ ,3]

mat3[2, ]

mat3[ ,c(1,3)]

my.data <- 1:20

my.data

A <- matrix(my.data, 4, 5)

A

A[2,3]

B <- matrix(my.data, 4, 5, byrow = TRUE)

B

B[2,5]

# rbind()

r1 <- c(“I”, “am”, “happy”)

r2 <- c(“What”, “a”, “day”)

r3 <- c(1, 2, 3)

C <- rbind(r1, r2, r3)

C

# cbind()

c1 <- 1:5

c2 <- -1:-5

D <- cbind(c1, c2)

D

D[1,2]

# Named vectors

Charlie <- 1:5

Charlie

names(Charlie)

names(Charlie) <- c(“N1”, “N2”, “N3”, “N4”, “N5”)

Charlie

Charlie[“N4”]

names(Charlie)

# Clear names

names(Charlie) <- NULL

Charlie

# Naming matrix dimensions

temp.vec <- rep(c(“James”, “Harvey”, “Alan”), each = 3)

# instead of times, we replicate the names 3 times each

temp.vec

bravo <- matrix(temp.vec, nrow = 3, ncol = 3)

bravo

row.names(bravo) <- c(“First”, “Second”, “Third”)

colnames(bravo) <- c(“Name1”, “Name2”, “Name3”)

bravo

bravo[“First”, ]

row.names(bravo)

bravo[“Third”, “Name1”] <- “Denny”

bravo

# Matrix Operations

mat3

mat3 <- mat3 – 1

mat3

# checking the dimensions of a matrix

dim(mat3) # number of rows and columns

mat2

mat4 <- mat2 + mat3

# not the same number of rows and columns in the individual matrices

mat4 <- mat3 + mat3

mat4

# interchanging the rows and columns in a matrix is known as transpose

print(mat4)

mat5 <- t(mat4)

mat5

# combining matrices:

# columnwise, only when we have the same number of rows

# rowise, only when we have the same number of columns

mat6 <- matrix(c(10, 11, 12), nrow = 3, ncol = 1)

mat6

combined.c <- cbind(mat5, mat6)

combined.c

combined.r <- rbind(mat4, mat5)

combined.r