Loop through large number of files and access arrays outside the loop ?

 for i = 1:50000
     f = fopen(sprintf('F%d', i), 'r'); %File names are F1, F2 and son on.
     X{i} = fscanf(f, '%d %d %f %d',[4, inf]); % Matlab nag about prellocating memory.
     X{i} = X{i}';
     A{i} = X(:,1:3); %Want to access only three columns of X{i} and make it A(i) and access it outside loop. 
     fclose(f);  
 end

 U = union(A(:,1:2),,'rows'); %Take union of first two colums of all A(i)

 for j = 1:50000
     Ua(j) = setdiff(U(:,1:2), A(:,1:2),'rows');%Again access A(i) from previous loop
     Ua_z(j) = [Ua(j) zeros(size(Ua,1),1)]; % Add zero column to Ua(j)
     AU(j) = [A(i) ; Ua_z(j)]; % Vertically concatenate A(i) and Ua_z(j)
     AU_sorted(j) = sortrows(AU); %Sort rows of AU(j)
 end

 C = [U(:,1:2), AU_sorted(:,3)]; % Horizontally concatenate U and AU_sorted(j)

[Thorsten]

So what's your question?

[Walter Roberson]

Duplicates http://uk.mathworks.com/matlabcentral/answers/256950-loop-through-large-number-of-files-and-access-data-outside-the-loop