Open In App

How to Create a New Matrix From All Possible Row Combinations in MATLAB?

Improve
Improve
Like Article
Like
Save
Share
Report

A  matrix represents a collection of numbers arranged in an order of rows and columns. A matrix encloses the elements in parentheses or brackets.  We will learn how to create a new matrix from all possible row combinations of rows of a different matrix and display the combinations. 

Procedure of Making a Matrix:

  • Declare the number of rows.
  • Declare a number of columns
  • Using the ‘rand’ function to pick random rows from a matrix.
  • Select rows randomly
  • Print matrix.

We can see the below examples to create a new matrix from all possible row combinations.

Syntax:

variable = randperm(parameter , parameter); %for taking random numbers

From the command randperm() it uses random numbers to make a matrix of row combinations.

Example:

Matlab




% MATLAB code to Create a matrix randomly
% picking rows from a Matrix 
 % size of given matrix 
i = 5; j = 4 ; 
a = rand(i,j) ; 
  
 % pick rows from matrix a
pick = 5 ;
  
 % select rows randomly 
id = randperm(i,pick) ;  
iwant = a(id,:) ; 
disp(iwant);


Output:

 

  

Explanation:

In the above example, we are declaring the number of rows, and columns, and declaring a variable that stores random numbers and makes a matrix. In the above, we are taking random numbers in the matrix but we can also declare typically.

Create a Matrix by Selecting All Rows Randomly:

Now we are creating a matrix by selecting all rows randomly. In this, we will declare a number of rows and columns and we create columns through another. 

Below are the examples through which we can understand.

Syntax:

variable1 = rand(rows,columns); %make a matrix of nth rows and m columns.

variable2 = randperm(nth_rows); %select rows randomly

Explanation:- rand() command makes a matrix of rows and columns and randomly stores a number.

Example:

Matlab




% MATLAB code for create a matrix 
% randomly picking rows from a Matrix 
% size of given matrix
i = 5; j = 6 ;   
A = rand(i,j) ; 
  
% select rwos randomly 
indx = randperm(i) ;   
iwant = A(indx,:) ; 
disp(iwant);


Output:

 

Explanation:

 In this, we are declaring i =5, j=6 ( number of rows and columns ) and we create columns through another.  This means we are creating a matrix of possible row combinations and at last, we will display it on our screen.

Create a 3D Matrix Selecting Rows Randomly: 

In this, we will create a 3D matrix by selecting randomly a row and we will display the new matrix on the screen. Below is a suitable example to understand.

Syntax:

var = perms(rows); % this will arrange all rows randomly

perms() command will arrange all rows randomly and the rand() command will take random numbers. For implementation check out the below example.

Example:

Matlab




% MATLAB code for  Create a matrix 
% randomly picking rows from a Matrix 
 % size of given matrix 
i = 3; j = 5 ; 
Ax = rand(i,j) ; 
  
% pick rows from matrix As
% arrange all rows randomly 
indx = perms(i) ;   
N = size(indx,1) ;
iwant = Ax(i,j,N) ; 
for k = 1:N
    iwant(:,:,k) = Ax(indx(k,:),:) ;
end
disp(iwant);


Output:

 

Explanation:

In this we are declaring i =3, j=5 ( number of rows and columns ) and we create columns through another.  This means we are creating a matrix of possible row combinations and at last, we will display it on our screen.



Last Updated : 23 Nov, 2022
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads