Convert a vector into a diagonal matrix in R

In this article, we will examine various methods to convert a vector into a diagonal matrix by using R Programming Language.

What is a diagonal matrix?

A diagonal matrix is a special type of square matrix where all elements, except those on the main diagonal (running from the top-left to the bottom-right), are zeros. This diagonal matrix can contain data of many types such as strings, integers, characters, and logic. It is possible to access the diagonal elements by using the built-in functions provided by R.

Converting a vector into a diagonal matrix

R language offers various methods to efficiently convert a vector into a diagonal matrix. By using these methods provided by R, it is easy to convert a vector into a diagonal matrix. Some of the methods to convert a vector into a diagonal matrix are

Converting a vector into a diagonal matrix by using the diag() function

This method is used to convert a vector into a diagonal matrix more efficiently.

Syntax

diag(y, nrow = NULL, ncol = NULL, diag = FALSE)

In the below example, we converted a vector into 5*5 diagonal matrix.

R

#declaring a vector
a=c(7,6,4,3,2)
print("The vector is")
print(a)

#creating diagonal matix
res=diag(a,ncol=5)
print("The diagonal matrix ")
print(res)

Output:

[1] "The vector is"
[1] 7 6 4 3 2

[1] "The diagonal matrix "
     [,1] [,2] [,3] [,4] [,5]
[1,]    7    0    0    0    0
[2,]    0    6    0    0    0
[3,]    0    0    4    0    0
[4,]    0    0    0    3    0
[5,]    0    0    0    0    2

In the below example, we converted a vector into 6*6 diagonal matrix.

R

#declaring a vector
vec=c(20,25,30,35,40,45)
print("The vector is")
print(vec)

#creating diagonal matix
res=diag(vec,ncol=6)
print("The diagonal matrix is")
print(res)

Output:

[1] 20 25 30 35 40 45

[1] "The diagonal matrix is"
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]   20    0    0    0    0    0
[2,]    0   25    0    0    0    0
[3,]    0    0   30    0    0    0
[4,]    0    0    0   35    0    0
[5,]    0    0    0    0   40    0
[6,]    0    0    0    0    0   45

Converting a vector into a diagonal matrix by using matrix multiplication

These method is used to convert a vector into a digonal matrix by using functions provided by R.

Syntax

res = matrix1%*%matrix2

In the below example, we converted a vector into the 4*4 diagonal matrix.

R

# declaring a vector
vec1 = c(9,8,6,5)
print("The vector is")
print(vec1)

# Converting vector into diagonal matrix
res<- diag(vec1) %*% t(diag(length(vec1)))

print("The diagonal matrix is")
print(res)

Output:

[1] "The vector is"
[1] 9 8 6 5

[1] "The diagonal matrix is"
     [,1] [,2] [,3] [,4]
[1,]    9    0    0    0
[2,]    0    8    0    0
[3,]    0    0    6    0
[4,]    0    0    0    5

In the below example, we converted a vector into 6*6 diagonal matrix

R

# declaring a vector
vec2 = c(20,25,30,35,40,45)
print("The vector is")
print(vec2)

# Converting vector into diagonal matrix
res<- diag(vec2) %*% t(diag(length(vec2)))

print("The diagonal matrix is")
print(res)

Output:

[1] "The vector is"
[1] 20 25 30 35 40 45

[1] "The diagonal matrix is"
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]   20    0    0    0    0    0
[2,]    0   25    0    0    0    0
[3,]    0    0   30    0    0    0
[4,]    0    0    0   35    0    0
[5,]    0    0    0    0   40    0
[6,]    0    0    0    0    0   45

Conclusion

In conclusion, we learned various methods to convert the vector into a diagonal matrix. R language offers versatile tools, while converting the vector into a diagonal matrix.