How to bypass empty fields in structure when loading data?

My experiment contains my subjects data and each subject consists of different blocks before I do the analysis I merged my data into one mat file, but some of my subjects have missing blocks, so I bypassed those data and merge the file. However the problem is missing blocks represent like this [ ], since some blocks are like this [ ], when I want to load different field of my structure I get this error '' Dot indexing is not supported for variables of this type '' Therefore I need to bypass these blocks in the loop, In this regard I added this code

 if isempty(all_Subjects(block_Counter, subject_Counter).all_results) == 0
     % do the workk
 else
     break
 end

but I got empty results for saving my data in table

% merging Information of different Subjects
Subjects_ID = [];
Blocks_ID = [];
reactionTime_of_all_Subjects = [];
performance_of_all_Subjects = [];

for subject_Counter = s_Initial:s_Final
    
    % select data with fields
 if isempty(all_Subjects(block_Counter, subject_Counter).all_results) == 0
    
    % merging Information of different blocks
    all_reactionTime_of_one_Subject = [];
    all_subject_Performance_of_one_Subject = [];
    
    for block_Counter =  B_Initial:B_Final
        
        reactionTime =  all_Subjects(block_Counter, subject_Counter).all_results.reactionTime;
        subject_Performance =  all_Subjects(block_Counter, subject_Counter).all_results.performance;
        
         % merging Information of different blocks
        all_reactionTime_of_one_Subject = [all_reactionTime_of_one_Subject; reactionTime];
        all_subject_Performance_of_one_Subject = [all_subject_Performance_of_one_Subject; subject_Performance];
        
        % Generate label for Subjects
        for i = 1: length(reactionTime)
            
            Subjects_ID = [Subjects_ID; subject_Counter]
            Blocks_ID = [Blocks_ID; block_Counter]
        end
    end
    
    % merging Information of different Subjects
    performance_of_all_Subjects = [performance_of_all_Subjects; all_subject_Performance_of_one_Subject];
    reactionTime_of_all_Subjects = [reactionTime_of_all_Subjects; all_reactionTime_of_one_Subject];
     else
        break
end
   
end
% Mering all data to table
analysis = array2table([Subjects_ID, Blocks_ID, reactionTime_of_all_Subjects, performance_of_all_Subjects]);
analysis.Properties.VariableNames{1} = 'Subjects_ID';
analysis.Properties.VariableNames{2} = 'Block_ID';
analysis.Properties.VariableNames{3} = 'ReactionTime';
analysis.Properties.VariableNames{4} = 'Performance';

save('data_for_Analysis','analysis')

[Image Analyst]

Please attach all_Subjects:

save('answers.dat', 'all_Subjects');

with the paper clip icon so we can run your code.

[Stephen23]

@Ali Motahharynia: please show the complete error message. This means all of the red text.

[Ali Motahharynia]

Here is the code and the all_Subjects attachment

and this is the error

Dot indexing is not supported for variables of this type.

reactionTime = all_Subjects(block_Counter,

subject_Counter).all_results.reactionTime;

thank you

% Merging subjects data
s_Initial = 1;
s_Final = 3;
B_Initial = 1;
B_Final = 2;
Subjects_ID = [];
Blocks_ID = [];
% merging Information of different Subjects
Subjects_ID = [];
Blocks_ID = [];
reactionTime_of_all_Subjects = [];
performance_of_all_Subjects = [];

for subject_Counter = s_Initial:s_Final
    
    % select data with fields
%  if isempty(all_Subjects(block_Counter, subject_Counter).all_results) == 0
    
    % merging Information of different blocks
    all_reactionTime_of_one_Subject = [];
    all_subject_Performance_of_one_Subject = [];
    
    for block_Counter =  B_Initial:B_Final
        
        reactionTime =  all_Subjects(block_Counter, subject_Counter).all_results.reactionTime;
        subject_Performance =  all_Subjects(block_Counter, subject_Counter).all_results.performance;
        
         % merging Information of different blocks
        all_reactionTime_of_one_Subject = [all_reactionTime_of_one_Subject; reactionTime];
        all_subject_Performance_of_one_Subject = [all_subject_Performance_of_one_Subject; subject_Performance];
        
        % Generate label for Subjects
        for i = 1: length(reactionTime)
            
            Subjects_ID = [Subjects_ID; subject_Counter]
            Blocks_ID = [Blocks_ID; block_Counter]
        end
    end
    
    % merging Information of different Subjects
    reactionTime_of_all_Subjects = [reactionTime_of_all_Subjects; all_reactionTime_of_one_Subject];
    performance_of_all_Subjects = [performance_of_all_Subjects; all_subject_Performance_of_one_Subject];
%      else
%         break
% end
   
end


analysis = array2table([Subjects_ID, Blocks_ID, reactionTime_of_all_Subjects, performance_of_all_Subjects]);
analysis.Properties.VariableNames{1} = 'Subjects_ID';
analysis.Properties.VariableNames{2} = 'Block_ID';
analysis.Properties.VariableNames{3} = 'ReactionTime';
analysis.Properties.VariableNames{4} = 'Performance';

save('data_for_Analysis','analysis')

[Image Analyst]

This code ran fine with no errors, with essentially no change to your code.

fprintf('Beginning to run %s.m.\n', mfilename);
s = load('all_subjects.mat')
all_Subjects = s.all_Subjects

% Merging subjects data
s_Initial = 1;
s_Final = 3;
B_Initial = 1;
B_Final = 2;
Subjects_ID = [];
Blocks_ID = [];
% merging Information of different Subjects
Subjects_ID = [];
Blocks_ID = [];
reactionTime_of_all_Subjects = [];
performance_of_all_Subjects = [];

for subject_Counter = s_Initial:s_Final
	% select data with fields
	%  if isempty(all_Subjects(block_Counter, subject_Counter).all_results) == 0
	
	% merging Information of different blocks
	all_reactionTime_of_one_Subject = [];
	all_subject_Performance_of_one_Subject = [];
	
	for block_Counter =  B_Initial:B_Final
		reactionTime =  all_Subjects(block_Counter, subject_Counter).all_results.reactionTime;
		subject_Performance =  all_Subjects(block_Counter, subject_Counter).all_results.performance;
		
		% merging Information of different blocks
		all_reactionTime_of_one_Subject = [all_reactionTime_of_one_Subject; reactionTime];
		all_subject_Performance_of_one_Subject = [all_subject_Performance_of_one_Subject; subject_Performance];
		
		% Generate label for Subjects
		for i = 1: length(reactionTime)
			Subjects_ID = [Subjects_ID; subject_Counter]
			Blocks_ID = [Blocks_ID; block_Counter]
		end
	end
	
	% merging Information of different Subjects
	reactionTime_of_all_Subjects = [reactionTime_of_all_Subjects; all_reactionTime_of_one_Subject];
	performance_of_all_Subjects = [performance_of_all_Subjects; all_subject_Performance_of_one_Subject];
	%      else
	%         break
	% end
	
end

analysis = array2table([Subjects_ID, Blocks_ID, reactionTime_of_all_Subjects, performance_of_all_Subjects]);
analysis.Properties.VariableNames{1} = 'Subjects_ID';
analysis.Properties.VariableNames{2} = 'Block_ID';
analysis.Properties.VariableNames{3} = 'ReactionTime';
analysis.Properties.VariableNames{4} = 'Performance';

save('data_for_Analysis.mat','analysis')
fprintf('Done Running %s.m.\n', mfilename);

[Ali Motahharynia]

thank you for that, and sorry I made a little mistake in sendining the code for the second time, if we put B_Final value to 3 we got the error and that's my problem, the all_Subjects results contain a 3*3 structure, but the row 3 of the structure have 2 missing blocks(1 and 3), and only the second has value, so when the code want to read the file it crashes and say ''Dot indexing is not supported for variables of this type.

Error in merger (line 25)

reactionTime = all_Subjects(block_Counter,

subject_Counter).all_results.reactionTime;''

Answer 1

[Ameer Hamza]

Use isstruct(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/isstruct.html. For example, use the following if condition to only access data of it is a struct

if isstruct(all_Subjects(block_Counter, subject_Counter).all_results)
    reactionTime =  all_Subjects(block_Counter, subject_Counter).all_results.reactionTime;
    subject_Performance =  all_Subjects(block_Counter, subject_Counter).all_results.performance;
else
    reactionTime =  0; % or something else
    subject_Performance = 0;
end

[Ali Motahharynia]

thanks for your answer both isempty and isstruct work very well but my mistake is that I put ''if'' in wrong place and thanks to you I figured that out, moreover if I put break after else it will be better and it won't add one 0 to the end of my data.

thank you