I am having empty cells while saving the extracted features inside loops

Hi,

Can someone help me with my code below. I am extracting features inside a loop from .csv files however, while I saved the features, I found that only one cell has the extracted values while the remaining cells were empty. I dont know where I miss it, please.

%% Function to read .csv frames
function Feature_Engineering
fb = fopen('NameListP500.txt','r');
FileNameP = fgetl(fb);
RoundP = str2num(FileNameP);
Extracted = {};
for Ct = 1:RoundP
    FileNameP = fgetl(fb);
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    fr = fopen('NameList500.txt','r');
    FileName = fgetl(fr);
    Round = str2num(FileName);
    for Ct = 1:Round                 
        try
            FileName = fgetl(fr);
            [Extracted] = Feature_Engineering(FileName,FileNameP,Ct,Extracted);
            
        catch ME
            disp('mistake to read frame number'); disp(Ct); 
        end 
        
        %imtool close all
        %close all 
    end
end

Answer 1

[CAM]

You never tell Matlab to put the next value of Extracted into a new cell. I.e., you have not increased the cell array index with each iteration of Ct. I suggest preallocating Extracted before the Round for-loop, then write a new value to Extracted(Ct) in each iteration.

By the way you also use the variable Ct to loop both Round and RoundP; I am surprised Matlab has not given you an error.