data analytics

1. Matrices
by
L Surya
Department of CSA
KL Deemed to be university
Vijayawada, AP, India
Department of computer science and application

2. Contents
Applications of matrices
Creation of a matrix in R
 Perform mathematical operations on matrices
Access the elements of a matrix
Department of computer science and application

3. Department of computer science and technology
Outcomes
• Know the applications of matrices
• Creating a matrix
• Perform mathematical operations on matrices
• Access the elements of a matrix
At the end of this lecture you will be
able to

4. Applications of matrices
• Computer graphics
• Probability and statistics
• Game theory
• Algorithms
• Quantum mechanics

5. Matrix
Definition: Matrix is a collection of
elements of the same type and data
arranged in two dimensional.

6. [,1] [,2] [,3]
[1,] 10 11 12
[2,] 13 14 15
[3,] 16 17 18
[4,] 19 20 21
Matrix
[,1] [,2] [,3] [,4]
[1,] 100 101 102 103
[2,] 104 105 106 107
[3,] 108 109 110 111
[4,] 112 113 114 115
Department of computer science and technology

7. Matrix creation
A matrix is created using
The matrix() function.
Syntax:
matrix_name<-
matrix(data,nrow,ncol,byrow,dimnames)
Where
Data – means input
nrow- number of rows
ncol – number of columns
byrow- means logical . If TRUE then the input vector
elements are arranged by row.
dimnames-is the names for the rows and columns.

8. Matrix creation
> x
[,1] [,2] [,3]
[1,] 10 11 12
[2,] 13 14 15
[3,] 16 17 18
Department of computer science and technology

9. Matrix creation
[,1] [,2] [,3] [,4]
[1,] 100 101 102 103
[2,] 104 105 106 107
[3,] 108 109 110 111
[4,] 112 113 114 115
[,1] [,2] [,3]
[1,] 10 14 18
[2,] 11 15 19
[3,] 12 16 20
[4,] 13 17 21

10. Adding row & col names
[,1] [,2] [,3]
[1,] 10 11 12
[2,] 13 14 15
[3,] 16 17 18
[4,] 19 20 21
col1 col2 col3
row1 10 11 12
row2 13 14 15
row3 16 17 18
row4 19 20 21

11. Adding row & col names

12. Accessing the elements of matrix
Access the elements of a matrix by using
The column and row index of the element.
Syn:Matrix_name[row,column]
Ex: to access 3rd
row 2nd
column
>x[3,2]

13. Accessing the elements of matrix
[,1] [,2] [,3]
[1,] 10 11 12
[2,] 13 14 15
[3,] 16 17 18
[4,] 19 20 21
To access column
>
To access row column
>
To access only row
>
To access only column
>

14. Operations on matrices
Operations that can be done on matrices are
Arithmetic operations
-->Addition
-->Subtraction
-->Multiplication
-->Division

15. Matrices
>x=matrix(c(10:18),nrow=3,
byrow=TRUE)
>y=matrix(c(1:9),nrow=3,
byrow=TRUE)
>
[,1] [,2] [,3]
[1,]
[2,]
[3,]
[,1] [,2] [,3]
[1,]
[2,]
[3,]
[,1] [,2] [,3]
[1,]
[2,]
[3,]

16. Thank You