In a cell array (which contains num. vectors of different lengths [ex.1x159871]), pad the ends of each cell with 'NaN' according to the longest row [ex. 1x249359]

Dear matlab,

I have a cell array with 17 sets of EEG signal data 'housed' in one mother cell array (ex. one cell is 1x159871 single).

Because they all have different column lengths, I want to pad the ends of each cell with 'NaN' according to the longest signal, so that in the end, I can create/convert the cell array into a mother uber matrix (which, of coarse, requires that all data have the same dimensions).

As I'm unfamiliar with how to perform operations of cell array data, any help or guidance would be greatly appreciated!

Thanks as always!

Joanne

ps., below is a sample code, I found from Fabio Freschi in 2019 (I just couldn't figure out how to reverse the dimensions in the first line of code to make it, for example, 1x47, instead of 47x1 and then to successfully execute the 2nd line of code without error popup):

https://www.mathworks.com/matlabcentral/answers/487635-pad-with-nan-according-to-maximum-row-in-cell#answer_398389

% the data
A = {rand(47,1),rand(80,1),rand(97,1)};

% pad with NaNs
A = cellfun(@(x)[x(1:end); NaN(97-length(x),1)],A,'UniformOutput',false);
 
% make a matrix
A = cell2mat(A);

Answer 1

[Voss]

Here's that same example, but each cell contains a row vector:

% the data
A = {rand(1,47),rand(1,80),rand(1,97)};

% pad with NaNs
N = max(cellfun(@numel,A)); % making a variable instead of hard-coding 97
A = cellfun(@(x)[x, NaN(1,N-length(x))],A,'UniformOutput',false); % concatenate horizontally (,) instead of vertically (;)
 
% make a matrix
A = cell2mat(A(:)); % use (:) to make A a column; thus each cell's content becomes a row in matrix A

disp(A);

  Columns 1 through 19

    0.1427    0.1909    0.6562    0.8677    0.5249    0.5001    0.5126    0.4950    0.4015    0.7480    0.6064    0.2965    0.4470    0.8540    0.0620    0.7962    0.0655    0.4210    0.5483
    0.7320    0.1553    0.4528    0.9172    0.7943    0.4984    0.0920    0.5065    0.7670    0.8833    0.9413    0.7070    0.9081    0.8201    0.2676    0.2575    0.9572    0.2423    0.5219
    0.3583    0.9180    0.0653    0.6659    0.6691    0.5958    0.0771    0.3895    0.3259    0.7552    0.1235    0.7552    0.0255    0.5133    0.0838    0.9204    0.7070    0.0415    0.2399

  Columns 20 through 38

    0.8091    0.8324    0.9735    0.7625    0.1639    0.0137    0.5246    0.4360    0.1754    0.5830    0.6037    0.7346    0.8412    0.5184    0.9988    0.8760    0.4937    0.2619    0.9185
    0.3342    0.0323    0.9154    0.6843    0.5786    0.3842    0.9591    0.8368    0.1709    0.7891    0.3301    0.9159    0.0464    0.0601    0.7611    0.7539    0.5120    0.7278    0.5848
    0.4920    0.5417    0.1672    0.8984    0.5200    0.7526    0.1059    0.1004    0.8803    0.2670    0.1957    0.5120    0.1007    0.3480    0.8405    0.5090    0.8894    0.4093    0.1431

  Columns 39 through 57

    0.2618    0.5571    0.8303    0.3652    0.7710    0.5562    0.2191    0.4117    0.6547       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN
    0.4742    0.9229    0.9511    0.8459    0.2976    0.4156    0.4330    0.7915    0.4047    0.3121    0.3790    0.2918    0.0253    0.7953    0.5918    0.8061    0.6460    0.1004    0.4503
    0.7675    0.2222    0.4206    0.7943    0.5298    0.6040    0.8725    0.9291    0.2157    0.8000    0.4759    0.4000    0.7737    0.6820    0.1131    0.0327    0.1915    0.0792    0.0077

  Columns 58 through 76

       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN
    0.9355    0.1498    0.9912    0.6019    0.9614    0.6260    0.5599    0.7205    0.8247    0.6861    0.3026    0.8810    0.2659    0.8608    0.3857    0.0769    0.9168    0.4857    0.4562
    0.6330    0.2744    0.2874    0.1594    0.2741    0.4156    0.9193    0.1708    0.9804    0.5308    0.4886    0.2354    0.7723    0.9535    0.6051    0.3572    0.3569    0.1218    0.4919

  Columns 77 through 95

       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN
    0.1264    0.5181    0.6564    0.9865       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN
    0.8938    0.7682    0.8717    0.5886    0.2757    0.7473    0.1987    0.0763    0.2584    0.9651    0.0983    0.6667    0.9683    0.6575    0.4010    0.6357    0.6975    0.2726    0.9250

  Columns 96 through 97

       NaN       NaN
       NaN       NaN
    0.6214    0.2073

[Joanne Hall]

This is so beautiful, I'm so happy - THANK YOU!!!

[Voss]

YOU'RE WELCOME!!!