Preallocation of a vector of structure

Hello everyone,

I've been trying to preallocate a vector in which each cell will be a structure of 42 fields like thi:

data = zeros(1,9);
for i=1:9
    if(i~=5)
        data(i) = load(['DPsv0000',num2str(i),'.mat']);
    end
end

Because I need the nine different structures in the same vector for the rest of the code and I want it to be time efficient. However, I can't seem to find a way for the preallocation to work. In fact, doing this, I get the following error:

Conversion to double from struct is not possible.

Error in MECA0062_Gaspar_1 (line 135)

data(i) = load(['DPsv0000',num2str(i),'.mat']);

Can anyone know if it is even possible to do what I'm trying?

Thanks everyone, have a good day!

Audric

Answer 1

[dpb]

You preallocated a double array and then tried to put a struct variable into it. As you discovered, "You can't do that!"

There's not the equivalent per se of preallocating a struct array of empty array elemnts; you just iterate and go on...

d=dir('DPsv0000*.mat']);            % return desired .mat files directory listing
for i=numel(d)
  if contains(d(i).name,'5'), continue, end
  data(i)=load(d(i).name);
end

Answer 2

[Peter Perkins]

Audric, it seems like dpb understand what you are doing better than I do, but "in which each cell will be a structure of 42 fields" sounds like maybe you are overcomplicating, and that you want an Nx42 table.

Answer 3

[Stephen Cobeldick]

n = 9;
P = 'absolute or relative path to where the files are saved';
C = cell(1,n);
V = setdiff(1:n,5);
for k = V
    F = sprintf('DPsv%05d.mat',k);
    C{k} = load(fullfile(P,F));
end
S = [C{:}]