Need Help Appending data to a table in every iteration from a for loop .I want to add new data to New_Table every loop but not overwrite the existing data.

filename = 'Notes.xls';
sheet = 1;
T = readtable(filename);
App_Names= T(:,4);
Unique_Data = unique(App_Names);
N = height (Unique_Data);
M = height(T);
 for j = 1: N

      app_name = Unique_Data{j,1}
      p = (strcmpi(app_name,T{:,:}))
      [row,col] = find(p)

      New_Table = [ T(row,1),T(row,2),T(row,3),T(row,4);]
      end

Answer 1

[KSSV]

T = table(rand(2,1),rand(2,1),'VariableNames',{'Age','Weight'},'RowNames',{'P1','P2'}) ;
for i = 3:10
    Tnew = table(rand,rand,'VariableNames',{'Age','Weight'},'RowNames',{['P',num2str(i)]}) ;
    T = [T ; Tnew] 
end

[s]

Thanks .It Worked great.T = [T ; Tnew] this actually helped.

Answer 2

[Peter Perkins]

I can't follow the original code at all, but in general, it's not a great idea, performance-wise, to groew a table in a loop. This is much faster:

c = cell(1,n)
for i = 1:n
   c{i} = table(...);
end
t = vertcat(c{:});

[Lautaro Parada]

way much faster! thanks!

[Julio Perez Olvera]

What if the variable names in tables inside "c" are not the same?

[Peter Perkins]

If the names are not the same, then why are you vertically concatenating them?

In my code snippet anobe, they will be the same (and set to the defaults), but if you want to vertically combine tables that have different variable names, then you have to reconcile the names, either by making the names on existing variables the same in all tables, or by adding variables to your tables to give them all the union of the different names.

That assumes that you want to turn all your tables into one longer table. Maybe you want a cell array, with a table in each cell, kept separately.