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Convert a non uniform cell array of cell arrays to matrix

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Tessa Kol
Tessa Kol on 20 Sep 2020
Answered: Sindar on 25 Sep 2020
I have the following code:
%% Loading the data
rhoPart = 2540;
files = dir(fullfile(uigetdir,'\**\*.data*'));
[~,Index] = natsort({files.name});
files = files(Index);
folders = {files.folder};
folder_groups = findgroups(folders);
k = 1;
for i = 1:length(files)
fid = fopen(fullfile(files(i).folder,files(i).name),'r');
%% Reading the data
% Read all the data from the file
dataRead = textscan(fid,'%f %f %f %f %f %f %f %f %f %f %f %f %f %f','HeaderLines',1);
frewind(fid);
% Write headerline N, time, xmin, ymin, zmin, xmax, ymax, zmax
runData{k} = strsplit(fgetl(fid), ' ');
% Write only the x, y, and z components of the particles, particle radius,
% z component+ particle radius and volume of the particle
expData{k} = [dataRead{1}(:,1) dataRead{2}(:,1) dataRead{3}(:,1) dataRead{7}(:,1) dataRead{3}(:,1)+dataRead{7}(:,1) rhoPart*(4/3)*pi*(dataRead{7}(:,1).^3)];
% Write only the vx,vy,vz of the particles and magnitude
velData{k} = [dataRead{4}(:,1) dataRead{5}(:,1) dataRead{6}(:,1) sqrt(dataRead{4}(:,1).^2 + dataRead{5}(:,1).^2 + dataRead{6}(:,1).^2)];
fclose(fid);
k = k + 1;
end
%% Classify (into a structure)
runData_struc = splitapply(@(x) {x}, runData, folder_groups);
expData_struc = splitapply(@(x) {x}, expData, folder_groups);
velData_struc = splitapply(@(x) {x}, velData, folder_groups);
This will give me the following cell array of runData_struct (see pictures)
As you can see this is a cell array in a cell array. I want to convert the 1x9 cell into a 1x9 double. For example:
runData_struc{1,1}
row 1: 1x9 double
row 2 :1x9 double
row 3: 1x9 double
...
row 2741: 1x9 double
runData_struc{1,2}
row 1: 1x9 double
row 2 :1x9 double
row 3: 1x9 double
...
row 2745: 1x9 double
I tried the following, but it gave me NaN as result:

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Sindar
Sindar on 23 Sep 2020
Yes, that answer was if the header line contained text, e.g.:
time position velocity
1 0 1
2 1 3
So you want to extract the numbers from the body and the words from the header.
Depending on how much time you'll be using this code, I'd suggest checking out my further suggestions - layers of cells tend to be more expensive and tedious to use than other data storage
Stephen Cobeldick
Stephen Cobeldick on 24 Sep 2020
If you reverse the order then you do not need to call frewind, giving simpler and more efficient code.
Simply read the header first and then the rest of the file data (the 1 specifies how many lines to read:
% Read headerline N, time, xmin, ymin, zmin, xmax, ymax, zmax
Headerline = textscan(fid,'%f%f%f%f%f%f%f%f%f',1);
% Read all the data from the file
dataRead = textscan(fid,'%f%f%f%f%f%f%f%f%f%f%f%f%f%f');
Tessa Kol
Tessa Kol on 25 Sep 2020
Thank you both for the suggestions and I will adapt my code according to it. Can I accept an answer to close this post?

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Accepted Answer

Sindar
Sindar on 25 Sep 2020
(see comments on question for details not related to the title question)
A1 = cell2mat(runData_struc{1});
A2 = cell2mat(runData_struc{2});
if that doesn't work, something like this might (but I'm not the cellfun expert)
A1 = cell2mat(cellfun(@cell2mat,runData_struc{1},'UniformOutput',false));
A2 = cell2mat(cellfun(@cell2mat,runData_struc{2},'UniformOutput',false));

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