How to Concatenate the result in for loop?

Hello every one

I'm very new in matlab

I have some problem how do i concatenate the result from for loop?

for i=0:bond(860)          %bond is the data table include 861*36 table of number
    a=[bond(i+1,:)];
    B=[repmat(a(1),[length(nonzeros(a))-1 1]) nonzeros(a(2:end)')];
end    
                                            

the result is

B =

16×2 uint32 matrix

860 796

860 797

860 798

860 816

860 817

860 818

860 819

860 836

860 837

860 838

860 839

860 840

860 857

860 858

860 859

860 861

B =

12×2 uint32 matrix

861 797

861 798

861 817

861 818

861 819

861 837

861 838

861 839

861 840

861 858

861 859

861 860

This is a few result it have number 1 - 861

it show just the lastest result in B table

I want to get all result since 1 to 861 in the same arrey (concatenate all result in one table), want all result in B table not only the lastest calculation

[Stephen23]

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

Use a cell array and contcatenate after the loop, just as your other threads explain:

https://www.mathworks.com/matlabcentral/answers/793597-how-to-separate-the-data-in-the-table-for-loop

https://www.mathworks.com/matlabcentral/answers/789789-how-to-connect-all-result

Answer 1

[Arjun]

Hi @Kris Sarikanoppakhun,

As per my understanding, the issue is that you are overwriting the variable "B" in each iteration of the loop and because of that result from the last iteration remains in variable "B".

To concatenate result from every iteration into "B", you need to initialize "B" before the loop and then instead of overwriting you append the fresh results into "B" in each iteration. Kindly refer to the modified version of the code below:

B = [];  % Initialize B before the loop
for i = 0:bond(860)
    a = bond(i+1, :);  
    temp = [repmat(a(1), [length(nonzeros(a)) - 1, 1]), nonzeros(a(2:end)')]; % Storing result of this iteration in a temporary variable
    B = [B; temp];  % Append the result to B
end
% At the end of the loop B will contain the result concatenated from all
% the iterations

I hope this helps!