MATLAB Answers

QuanCCC
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How to sum by identifier

Asked by QuanCCC
on 16 Sep 2018
Latest activity Edited by QuanCCC
on 25 Sep 2018
Hi there,
I have a table data: A column is the identifier data, column B C D is the data I want to sum up by the same A value.
How can I do that?
I tried 'accumarray', but it seems I mixed table and array. MATLAB says"Undefined function 'accumarray' for input arguments of type 'table'." Then I turned my data to an array, MATLAB says "All input arguments must be tables." And I do have 3 columns values to be summed up. Thank you.
[a,~,c] = unique(yourdata(:,1)); % 'yourdata(:,1)' 1 means column 1 is the identifier
output = [a, accumarray(c,yourdata(:,2))]; % 2 means the colume to be summed up.

  1 Comment

yourdata{:, 1} instead of (:, 1)

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1 Answer

Answer by Steven Lord
on 16 Sep 2018
 Accepted Answer

Use groupsummary with A as the grouping variable.

  1 Comment

If the sum up is for all data with the same identifier, a groupsummary is the best idea. If you have more data (more than needed for the sum up) with the same identifier, the codes I mentioned works.

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