Put several values into 1 cell (e.g. array{1} = [1,2,3]) for multiple condition SPM analysis; All I get is array{1} = [1] [2] [3] - matlab

Question

I'm working to get a 1st level analysis completed on some fMRI data, and as it's my first time using SPM in this way, it seems as though there is no end to my frustrations. SPM includes these specific instructions:
"This *.mat file must include the following cell arrays (each 1 x n): names, onsets, and durations. eg. names=cell(1,5), onsets=cell(1,5), durations=cell(1,5), then names{2}="Second condition", onsets{2}=[3,5,19,22],durations{2}=[0,0,0,0], contain the required details of the second condition."
The code I'm using grabs the data I need from the various excel files the behavioral data is stored in, and adds them to these cell arrays.
sessionFiles = dir('*.xlsx');
allNames = {sessionFiles.name}';
conditions = 36;
% go through excel files to grab relevant column information for SPM
for i=1:length(sessionFiles)
[~,fileName,~] = fileparts(allNames{i});
% initialize cells SPM needs
names = cell(1,conditions);
onsets = cell(1,conditions);
durations = {1.75};
durations = repmat(durations,1,conditions);
% read in excel file
[num,~,~] = xlsread(sessionFiles(i).name);
trialType = num(:,6);
% grab condition information from columns: seconds=9, name=6
for j=1:conditions
index = find(trialType==j);
trialOnsets = cell(1,length(index));
names{1,j} = j;
for k=1:length(index)
trialOnsets{1,k}=double(num(index(k),9));
end
onsets{1,j} = trialOnsets;
end
% save new data for SPM
save(fileName,'names','onsets','durations');
clear names onsets durations fileName num raw text
end
I found an example which shows each cell should look like this:
I just can't figure out how to grab the numbers automatically and put them in cells like that.
I know this isn't the SPM forums, but I've seen a few questions posted and I thought I would try my luck.

Answer 1

With the line trialOnsets = cell(1,length(index));, trialOnsets is specified as a cell array of size 1xlength(index). Then, trialOnsets is assigned to onsets{1,j}. With this workflow, each cell of onsets will be of size 1xlength(index).
Instead, each cell of onsets should be of size 1x1 and each 1x1 cell in onsets should have a matrix of size 1xlength(index). To do this, do the following.
Specify trialOnsets as a matrix, instead of as a cell array. To do this, replace trialOnsets = cell(1,length(index)); with trialOnsets = zeros(1,length(index));.
Assign the values from num to trialOnsets, which is now a matrix (previously was a cell array). To do this, replace trialOnsets{1,k}=double(num(index(k),9)); with trialOnsets(1,k)=double(num(index(k),9));.
The edited code should be as follows:
sessionFiles = dir('*.xlsx');
allNames = {sessionFiles.name}';
conditions = 36;
% go through excel files to grab relevant column information for SPM
for i=1:length(sessionFiles)
[~,fileName,~] = fileparts(allNames{i});
% initialize cells SPM needs
names = cell(1,conditions);
onsets = cell(1,conditions);
durations = {1.75};
durations = repmat(durations,1,conditions);
% read in excel file
[num,~,~] = xlsread(sessionFiles(i).name);
trialType = num(:,6);
% grab condition information from columns: seconds=9, name=6
for j=1:conditions
index = find(trialType==j);
trialOnsets = zeros(1,length(index));
names{1,j} = j;
for k=1:length(index)
trialOnsets(1,k)=double(num(index(k),9));
end
onsets{1,j} = trialOnsets;
end
% save new data for SPM
save(fileName,'names','onsets','durations');
clear names onsets durations fileName num raw text
end
I could not test this code, since there was no sample data. Let me know if this works for you.