Rolling window column selection

Hello,

Please help me with the following:

Consider a 365x1 matrix A.

I need to extract the new column vector as:

v1: the first 48 values 1-48

v2: the next 48 values 25-73

v3: the next 48 values 49-97

That means that the next vector has the last 24 of the previous vector plus the next 24.

Can this be done with a loop or other method?

Thank you.

Best,

Pavlos

[Adam Danz]

• 1:48 has 47 values.
• 25:73 has 48 values
• 49:97 has 48 values.

Did you mean for the first example to start with 0

• 0:48 has 48 values.

Also, since 365 isn't divisible by 24, is it OK that the last ~5 elements of data won't be represented in any of the new column vectors?

Answer 1

[Adam Danz]

Here's one solution that creates 14 column vectors in a manner your described. I stored fake data in column v, identified the start and stop indices of each new column, and then looped through each stop index to create a new matrix vSplit where each column contains a subsection of v.

If it turns out that each new column of data is not of equal length, you'll need to store the data in a cell array rather than a matrix.

v = rand(365, 1); 
startIdx = 1:24:length(v); 
stopIdx = 48:24:length(v); 

vSplit = zeros(48, length(stopIdx)); 
for i = 1:length(stopIdx)
    vSplit(:,i) = v(startIdx(i):stopIdx(i)); 
end

Answer 2

[Andrei Bobrov]

v = randi(1000,365,1);

out = v((1:24:numel(v) - 48)' + (0:47)); % version of MATLAB >= R2016a
out = v(bsxfun(@plus,(1:24:numel(v) - 48)',0:47)); % < R2016a