Error using reshape when creating a new cell array in a loop

Hi,

I have a cell array with 19 cells. Within each cell there is a matrix with 21 columns. Now I want to loop a piece of code over each of these columns within these matrices, for each of the cells.

When I run my code I get the error,

"Error using reshape

Product of known dimensions, 512, not divisible into total number of elements, 1108758."

This is the code:

[file_list, path_n] = uigetfile('.csv', 'Grab csv', 'Multiselect', 'on');
if ~iscell(file_list)
    file_list = {file_list};
end
participants = cell(length(file_list),1);
for i = 1:length(file_list)
    filename = file_list{i};
    data_in = readmatrix([path_n, filename]);
    participants{i} = data_in(:,7:27);
end

num_cells = size(participants);
num_columns = size(participants{i},2);
block_size = 512;
p_windows = {};
for j = 1:1:num_cells
    for k = 1:1:num_columns
        N = block_size*ceil(numel(participants{i},1)/block_size);
        participants{i,1}(end+1:N) = NaN;
        p_windows = reshape(participants{i,1},512,[]);
    end
end

My goal is to take each individual column from the matrices in participants and cut them into smaller 512 element long lists. These 512 long lists are then stored in matrices (one matrix per cut-up column) and saved in a new cell array (p_windows).

I hope this makes sense. Thanks in advance!

EDIT: Here is the variable participants (19x1 cell array with matrices in it) as a download link from weshare (it was too big to upload):

participants.mat

Answer 1

[Walter Roberson]

for j = 1:numel(participants)
    N = block_size*ceil(numel(participants{j},1)/block_size);
    participants{j,1}(end+1:N,:) = NaN;
    for k = 1:1:num_columns
        p_windows{j,k} = reshape(participants{j,1}(:,k),block_size,[]);
    end
end

[lil brain]

Hi Walter,

thanks for the reply!

However, I am getting the same error. Just this time with a different matrix I presume.

Error:

"Error using reshape

Product of known dimensions, 512, not divisible into total number of elements, 23925."