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.

Question

s 2018-9-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420600-need-help-appending-data-to-a-table-in-every-iteration-from-a-for-loop-i-want-to-add-new-data-to-ne

编辑： Peter Perkins 2020-7-28

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

KSSV 2018-9-25

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420600-need-help-appending-data-to-a-table-in-every-iteration-from-a-for-loop-i-want-to-add-new-data-to-ne#answer_338256

在 MATLAB Online 中打开

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

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

s 2018-9-25

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

请先登录，再进行评论。

Answer 2

Peter Perkins 2018-10-1

5
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420600-need-help-appending-data-to-a-table-in-every-iteration-from-a-for-loop-i-want-to-add-new-data-to-ne#answer_339256

在 MATLAB Online 中打开

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{:});

3 个评论
显示 1更早的评论隐藏 1更早的评论

Julio Perez Olvera 2020-5-21

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

Peter Perkins 2020-7-28

编辑：Peter Perkins 2020-7-28

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.

请先登录，再进行评论。