append to a table using findgroups and splitapply

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Qiana Curcuru 2021-7-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/882358-append-to-a-table-using-findgroups-and-splitapply

回答： Simon Chan 2021-7-20

I have a for loop that creates a table every iteration but i just want to append the new data table to the end of the last table that was made instead of over writing the table every iteration. how would i do that?

for i=1:10
    a = {...
      'apples' 1 2;...
      'orange' 2 3;...
      'apples' 3 4;...
      'Pear'   4 5;...
      'apples' 5 6;};
    % Extract the first 3 items
    a2 = a(1:3,:);
    % Apply findgroups
    [G, fields] = findgroups(a2(:,1));
    % Execute splitapply
    x = splitapply(@sum, cell2mat(a2(:,2)), G);
    % Summarize the result
    tResult = table(fields, x,...
      'VariableNames',{'Item','Value'});
    % Show the result
    disp(tResult)
end 

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Answer 1

Simon Chan 2021-7-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/882358-append-to-a-table-using-findgroups-and-splitapply#answer_750493

在 MATLAB Online 中打开

Create an empty cell and empty array before the loop.

Then create the table after the loop.

combinefields={};                                               % Empty cell
combinex = [];                                                  % Empty array
for i=1:10
    a = {...
      'apples' 1 2;...
      'orange' 2 3;...
      'apples' 3 4;...
      'Pear'   4 5;...
      'apples' 5 6;};
    % Extract the first 3 items
    a2 = a(1:3,:);
    % Apply findgroups
    [G, fields] = findgroups(a2(:,1));
    % Execute splitapply
    x = splitapply(@sum, cell2mat(a2(:,2)), G);
    % Summarize the result
    combinefields = vertcat(combinefields, fields);             % Combine 'fields'
    combinex = [combinex; x];                                   % Combine 'x'
end 
tResult = table(combinefields, combinex,...                     % Create table after finishing the loop
      'VariableNames',{'Item','Value'});
    %% Show the result
disp(tResult)