MATLAB: Finding average of every nth row

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I have a column vector that is 9985×1. I want to create a new vector that lists the average of every 6 rows in the column. How can I do this? Is there a way to do it with a loop?
Thank you!

Best Answer

This is the mean over 6 subsequent rows:
x  = rand(9985, 1);
S  = numel(x);
xx = reshape(x(1:S - mod(S, 6)), 6, []);
y  = sum(xx, 1).' / 6;
The trailing rows are ignored.
[EDITED] General method for matrices:
x  = rand(9985, 14);
p  = 6;
n  = size(x, 1);          % Length of first dimension
nc = n - mod(n, p);       % Multiple of p
np = nc / p;              % Length of result
xx = reshape(x(1:nC, :), p, np, []); % [p x np x size(x,2)]
y  = sum(xx, 1) / p;      % Mean over 1st dim
y  = reshape(y, np, []);  % Remove leading dim of length 1
See also FEX: BlockMean
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