Organising data into new matrix nxp

Question

scour_man 2011-7-8

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https://ww2.mathworks.cn/matlabcentral/answers/11162-organising-data-into-new-matrix-nxp

Hi! I have several matrices (Z1, Z2, Z3 etc.) all of which are 322x202 and are values of depths from seabed surveys (each depth value within a matrix is for a different position). All surveys cover an identical area but are from different times (months/years apart). There are corresponding matrices X and Y which hold the latitude and longitude positions allowing visualisation of data by contour plot etc.

What I would like to do (in order for some statistical analysis) is rearrange the data into one matrix nxp where n is the number of timesteps and p is the positions.

I understand how to do this for very small matrices by matrix indexing but this is extremely tedious and time consuming... how can I do it quickly for my large matrices?

Any help much appreciated

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Oleg Komarov 2011-7-8

So, do you want timestamp|lat|lon|value ?

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Answer 1

the cyclist 2011-7-8

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https://ww2.mathworks.cn/matlabcentral/answers/11162-organising-data-into-new-matrix-nxp#answer_15260

在 MATLAB Online 中打开

The fact that your original Zn matrices are named like that makes things a bit awkward. You might want to read this:

http://www.mathworks.com/matlabcentral/answers/143-how-do-i-make-a-series-of-variables-a1-a2-a3-a10

to learn ways to avoid that, if possible.

However, if you are stuck with those variable names, then you can do something like the following:

N = 2; % Number of individual Z arrays (i.e. time steps)
Z1 = rand(3,4);
Z2 = rand(3,4);
% Get all the individual Z arrays into one big one
Z = zeros(3,4,N);
for i = 1:N
    eval(['Z(:,:,i)=Z',num2str(i)]);
end
% Permute so that the time dimension is the first dimension
Z_time_first = permute(Z,[3 1 2]);
% Reshape so that the array is (number time steps X number observations)
Z_time_by_observations = reshape(Z,[2,12]);