# Average matrices based on unique value in structure resulting in a new structure

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nlm on 3 Oct 2018
Commented: nlm on 5 Oct 2018
I have a structure IMERG, with 19 fields. I have a field called "UID" based on which I want to average the fields of Lat and Lon which are 1*1700. For example, If UID is 1, then want to average all the Lat's with UID = 1 such that I get an 1 * 1700 for UID =1, and similarly for others.
I tried using arrayfucn, but it averages all the values within each IMERG(1).Lat, and also I'm unable to evaluate it based on unique values of UID. Please find the data attached of the structure I'm using.
A = arrayfun(@(x) mean(x.Lat),IMERG,'UniformOutput',1),
Any help is highly appreciated !! I have been trying this for very long now....

Akira Agata on 4 Oct 2018
How about using splitapply function, like:
IMERG = struct2table(IMERG);
avgLat = splitapply(@(x) {mean([x{:}],2)}, IMERG.Lat, IMERG.TimeID+1);
nlm on 4 Oct 2018
Thank you much :) "If column vector with the same length will be stored in each element, like IMERG.LAT, you can use the same way" I wanted to perform simultaneous average of the fields according to IMERG.UID with the same length as the field and store them into a new structure. Thanks again !

Akira Agata on 4 Oct 2018
To obtain the result in structure type, please combine struct2table, splitapply and table2struct functions like the following:
IMERG = struct2table(IMERG);
[group,UID] = findgroups(IMERG.UID);
avgLat = splitapply(@(x) {mean([x{:}],2)}, IMERG.Lat, group);
avgLon = splitapply(@(x) {mean([x{:}],2)}, IMERG.Lon, group);
avgIMERG = table(UID,avgLat,avgLon);
avgIMERG = table2struct(avgIMERG);
Using this code, averaged Lat and Lon, based on UID, will be stored in avgImerg structure.
nlm on 5 Oct 2018
Thanks ! :)

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