reducing the m x n value of matrix

Question

Pinky Incognito 2011-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/3445-reducing-the-m-x-n-value-of-matrix

Hi,

I have a matrix of 2500 x 56,

and I need to reduce the value to be half, i.e: 1250 x 56 or 1250 x 28

It's not that I want to compress the value, but I want the other 1250 just to be taken out. Meaning, i want my first 1250 original value. I hope i make sense here..

The matrix value is being save in data_all.mat.

Does anyone know how to access the row and column value?

I know about principal component analysis, but that is not what I want to do.

Thanks for the help..

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Answer 1

Walter Roberson 2011-3-18

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在 MATLAB Online 中打开

Try

A(1:1250,:)

and

A(1:ceil(end/2),1:ceil(end/2))

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Answer 2

Pinky Incognito 2011-3-18

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Thanks.. but can you explain more.

What does A stands for? is it my .mat file?

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Walter Roberson 2011-3-18

A is your matrix. load() your matrix from your .mat file if you need to. save() the reduced matrix back to your .mat file if you want to (but it's a good idea to save it to a _different_ .mat file until you are sure that everything worked and that you don't need the original data any more.)

Pinky Incognito 2011-3-18