make column in a matrix: 1,1,1,2,2,2,3,3,3 etc

Hi,

I'm trying to create a matrix A(21,4). In the second column I want to insert the numbers 1,1,1,2,2,2,3,3,3 etc until the end of the column. Tried this:

A = zeros(21, 4);

A(:,2) = rem((0:size(imageInformation,1)-1)',7)+1;

Which creates the column 1,2,3,4,6,7,1,2,3 etc. How can I modify this/is there any way to write code which would input the previously mentioned numbers into the matrix?

[Gal]

n = 3; repeats = 3;

x = repmat(0:1:n,repeats,1);
x = x(:)';

Answer 1

[Jos (10584)]

A(:,2) = ceil((1:size(A,1))/3)

Answer 2

[Matt Fig]

A(:,2) = reshape(cumsum(ones(3,7),2),21,1);

or

A(:,2) = floor(linspace(1,7.7,21));

Answer 3

[Image Analyst]

Try this:

A(:, 2) = [1,1,1,2,2,2,3,3,3,4,4,4,5,5,5,6,6,6,7,7,7]';

If you need it more general, then say so.

If you have the Image Processing Toolbox, you can do it more generally this way:

A = zeros(21,4);
[rows columns] = size(A);
secondColumn = imresize((1:rows/3)', [rows, 1], 'nearest')
A(:, 2) = secondColumn

Answer 4

[Wayne King]

One of many ways (requires Signal Processing Toolbox for upsample.m)

    x = (1:7)';
    x = repmat(x,1,4);
    A = upsample(x,3);
    A = filter(ones(3,1),1,A);

Answer 5

[Jan]

A(:, 2) = reshape(repmat(1:7, 3, 1), [], 1);

Answer 6

[Andrea]

Thank you everyone! Lots of great solutions. I ended up using the one Jos suggested, but I'm very grateful to you all! :)