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

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Andrea
Andrea 2012-11-20
评论： Gal 2015-10-15
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?

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采纳的回答

Jos (10584)
Jos (10584) 2012-11-20
A(:,2) = ceil((1:size(A,1))/3)

更多回答（5 个）

Matt Fig
Matt Fig 2012-11-20
编辑：Matt Fig 2012-11-20
A(:,2) = reshape(cumsum(ones(3,7),2),21,1);
or
A(:,2) = floor(linspace(1,7.7,21));
Image Analyst
Image Analyst 2012-11-20
编辑：Image Analyst 2012-11-20
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
Wayne King
Wayne King 2012-11-20
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);
Jan
Jan 2012-11-20
A(:, 2) = reshape(repmat(1:7, 3, 1), [], 1);
Andrea
Andrea 2012-11-20
Thank you everyone! Lots of great solutions. I ended up using the one Jos suggested, but I'm very grateful to you all! :)

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