MATLAB: How to permute one matrix columns according to rows in different matrix

MATLABpermutationsrandomrandperm

Hi,

I have a matrix A 60*31 , and i want to create a new matrix of B 1000*60, as followed:

Each row in B will include a single random value from each row in A. in total each row will be the size of 60 values. for example,

A=magic (4)

A =

    16     2     3    13
     5    11    10     8
     9     7     6    12
     4    14    15     1

than matrix B could be

i tried using randperm, or even creating an additional random index matrix, but apparently i'm doing something wrong. How can i do this?

Thanks!

Best Answer

To select 4 elements from A, one from each column:

index = randi([1,4], 1, 4) + (0:4:12)   % linear indexing
A(index)

For a [1000 x 4] matrix:

index = randi([1,4], 1000, 4) + (0:4:12)  % Arithmetic expanding: >= R2016b
B     = A(index);

For older Matlab versions use:

index = bsxfun(@plus, randi([1,4], 1000, 4), (0:4:12))

[EDITED] If you want rows instead of columns, simply transpose A at first.

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MATLAB: Random matrix with maximum values.

You could do this:

w = floor(sqrt(30))
rows = 1 : w
counter = 1;
for k = 1 : length(rows)
	columns(k) = floor(30/rows(k));
	for col = 1 : columns(k)
		fprintf('For %d rows, and %d columns, there are %d elements.\n',...
			rows(k), col, rows(k) * col);
		allMatrices{counter} = rand(rows(k), col);
		counter = counter + 1;
	end
end

You'll get every possible matrix size with 30 or fewer elements in it. And each one will be a cell in the allMatrices cell array. It has to be a cell array rather than a 3-D matrix because the matrices are not all the same size. You'll see in the command window:

w =

rows =

1 2 3 4 5

For 1 rows, and 1 columns, there are 1 elements.

For 1 rows, and 2 columns, there are 2 elements.

For 1 rows, and 3 columns, there are 3 elements.

For 1 rows, and 4 columns, there are 4 elements.

For 1 rows, and 5 columns, there are 5 elements.

For 1 rows, and 6 columns, there are 6 elements.

For 1 rows, and 7 columns, there are 7 elements.

For 1 rows, and 8 columns, there are 8 elements.

For 1 rows, and 9 columns, there are 9 elements.

For 1 rows, and 10 columns, there are 10 elements.

For 1 rows, and 11 columns, there are 11 elements.

For 1 rows, and 12 columns, there are 12 elements.

For 1 rows, and 13 columns, there are 13 elements.

For 1 rows, and 14 columns, there are 14 elements.

For 1 rows, and 15 columns, there are 15 elements.

For 1 rows, and 16 columns, there are 16 elements.

For 1 rows, and 17 columns, there are 17 elements.

For 1 rows, and 18 columns, there are 18 elements.

For 1 rows, and 19 columns, there are 19 elements.

For 1 rows, and 20 columns, there are 20 elements.

For 1 rows, and 21 columns, there are 21 elements.

For 1 rows, and 22 columns, there are 22 elements.

For 1 rows, and 23 columns, there are 23 elements.

For 1 rows, and 24 columns, there are 24 elements.

For 1 rows, and 25 columns, there are 25 elements.

For 1 rows, and 26 columns, there are 26 elements.

For 1 rows, and 27 columns, there are 27 elements.

For 1 rows, and 28 columns, there are 28 elements.

For 1 rows, and 29 columns, there are 29 elements.

For 1 rows, and 30 columns, there are 30 elements.

For 2 rows, and 1 columns, there are 2 elements.

For 2 rows, and 2 columns, there are 4 elements.

For 2 rows, and 3 columns, there are 6 elements.

For 2 rows, and 4 columns, there are 8 elements.

For 2 rows, and 5 columns, there are 10 elements.

For 2 rows, and 6 columns, there are 12 elements.

For 2 rows, and 7 columns, there are 14 elements.

For 2 rows, and 8 columns, there are 16 elements.

For 2 rows, and 9 columns, there are 18 elements.

For 2 rows, and 10 columns, there are 20 elements.

For 2 rows, and 11 columns, there are 22 elements.

For 2 rows, and 12 columns, there are 24 elements.

For 2 rows, and 13 columns, there are 26 elements.

For 2 rows, and 14 columns, there are 28 elements.

For 2 rows, and 15 columns, there are 30 elements.

For 3 rows, and 1 columns, there are 3 elements.

For 3 rows, and 2 columns, there are 6 elements.

For 3 rows, and 3 columns, there are 9 elements.

For 3 rows, and 4 columns, there are 12 elements.

For 3 rows, and 5 columns, there are 15 elements.

For 3 rows, and 6 columns, there are 18 elements.

For 3 rows, and 7 columns, there are 21 elements.

For 3 rows, and 8 columns, there are 24 elements.

For 3 rows, and 9 columns, there are 27 elements.

For 3 rows, and 10 columns, there are 30 elements.

For 4 rows, and 1 columns, there are 4 elements.

For 4 rows, and 2 columns, there are 8 elements.

For 4 rows, and 3 columns, there are 12 elements.

For 4 rows, and 4 columns, there are 16 elements.

For 4 rows, and 5 columns, there are 20 elements.

For 4 rows, and 6 columns, there are 24 elements.

For 4 rows, and 7 columns, there are 28 elements.

For 5 rows, and 1 columns, there are 5 elements.

For 5 rows, and 2 columns, there are 10 elements.

For 5 rows, and 3 columns, there are 15 elements.

For 5 rows, and 4 columns, there are 20 elements.

For 5 rows, and 5 columns, there are 25 elements.

For 5 rows, and 6 columns, there are 30 elements.

MATLAB: Corresponding values between two matrices

index=ismember(A(:,2),B(:,1));
A(index,1)

Best Answer

Related Solutions

MATLAB: Random matrix with maximum values.

MATLAB: Corresponding values between two matrices

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