How to sum by identifier

Question

QuanCCC 2018-9-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/419203-how-to-sum-by-identifier

编辑： QuanCCC 2018-9-25

采纳的回答： Steven Lord

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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.

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Walter Roberson 2018-9-16

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

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Answer 1

Steven Lord 2018-9-16

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/419203-how-to-sum-by-identifier#answer_337045

Use groupsummary with A as the grouping variable.

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QuanCCC 2018-9-25

编辑：QuanCCC 2018-9-25

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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