How to fill a matrix from 11,000x43 to 32,000x43 with Nans in order to concatenate arrays?

I am trying to generate a 3D array with 100 different files, however there are 30 files that are 11,000x43 and 70 that are 32,000x43. I would like to be able to make them the same size so I can concatenate them.

This is my example:

close all; clear all

P = 'D:\2021\datos_cozumel\DatosADCP2\';
S = dir(fullfile(P,'S1*.mat'));
S = natsortfiles(S); 
for k = 1:numel(S)
    F = fullfile(P,S(k).name);
    L = load(F);
    v1(k).data = L.Data.Burst_VelBeam1; 
end

vb1 = permute(cat(3,v1.data),[1,3,2]);
save('velbeam1_3.mat','vb1')

....

Thanks for your help

Answer 1

[Image Analyst]

Why do they have to be nan? Can they be zeros? If so the easy way is

close all; 
clear all

folder = 'D:\2021\datos_cozumel\DatosADCP2\';
S = dir(fullfile(folder,'S1*.mat'));
S = natsortfiles(S); 
for k = 1:numel(S)
    fullFileName = fullfile(folder,S(k).name);
    % Load the mat file.
    L = load(fullFileName);
    % Get the image from the recalled structure.
    thisMatrix = L.Data.Burst_VelBeam1;
    % Check it's size, expanding if necessary.
    if k == 1
        [rows, columns, numberOfColorChannels] = size(thisMatrix);
    else
        [rowsk, columnsk, numberOfColorChannelsk] = size(thisMatrix);
        if rowsk < rows || columnsk < columns
            % This matrix is smaller.  Expand it to the same size as the
            % first image.
            thisMatrix(rowsk, columnsk) = 0;
        end
    end
    % Assign to the data field of the k'th structure.
    v1(k).data = thisMatrix; 
end

vb1 = permute(cat(3,v1.data),[1,3,2]);
save('velbeam1_3.mat','vb1')

[Andres Ulloa]

Hi, thanks for your answer, each VelBeam1 file is inside Data, so when I try to use vb1 = permute(cat(3,v1.data),[1,3,2]); It throws me the error because there are files (Data.VelBeam1) with 11,000x43 and others 30,000x43, that is why I wanted to fill the 11,000x43 with Nans so that they were the same as the 30,000x43 ones to be able to concatenate correctly.

[Image Analyst]

Can you attach two .mat files, one with each size in it?

[Andres Ulloa]

I attach 2 examples, hope they help.