How to group a matrix based on one column?

Question

Sevgi 2023-5-9

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https://ww2.mathworks.cn/matlabcentral/answers/1960134-how-to-group-a-matrix-based-on-one-column

评论： Peter Perkins 2023-6-5

Hi,

I have a 64600x59 matrix data. I need unique values and also non-unique values grouped. Usually i use unique() function and then check if my rows matches with unique value rows, then i group by this using for loop. But this time my data is very big and it takes too much time.

I am curious about if there is any shortcut way or a function in matlab for me to group every same value in a different cell or table. This way i will be seeing non-unique values as grouped.

Do you have any ideas or suggestions?

Thank you

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Sevgi 2023-5-9

编辑：Sevgi 2023-5-9

Thank you for this suggestion. I study on it and the code work for now.

T=readtable("a.xslx");

[percombine, combinenames]= findgroups(T.Combine);

meanfirstaxle= splitapply(@mean,T.("1. Axle"),percombine);

I can take mean of each groups too. But I still can't see what are group members. Is there a way for it?

Peter Perkins 2023-6-5

There are any number of ways to do grouped calculations, includng groupsummary/transform/filter/counts, varfun/rowfun, and (as Stephen123 says) findgroups/splitapply.

But first you need to show exactly what you have and exactly what you want.

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