MATLAB: Find and collate matching values.

analysisfunctionMATLAB

Hi All,
Lets say I have multiple unique data sets:
data1.gamma = [1,2,3,4,5,6,7,8,9,10];
data1.eta   = [0.1,0.4,0.9,0,0.2,0.5,0.7,0.8,0.9,0.10];
data1.phi ........
data2.gamma = [0,2,0,4,5,9,7,10,9,6];
data2.eta   = [0.1,0.4,0.9,0,0.2,0.5,0.7,0.8,0.9,0.10];
data2.phi ........
and data3, data4 etc as such.
I would like to write a function that can to compare all the data sets and on each data set only keep variable values where
data.gamma
is the same. Any idea how I would go about doing that? I can compare and match 2 data sets. However I am not sure how to compare multiple data sets.
Also I do not know how many data set there will be (data1,data2,data3,data4….). So how do I make the function "scale-up" as necessary. Is that even possible without predefined the variable names?
Any help would be much appreciated.

Best Answer

Not sure what "keep" means, but to compare the two arrays, use isequal(). Try this:
if isequal(data1.gamma, data2.gamma)
    % They're equal

else
    % They're not equal.

end
It would be best if your datan were not unique as you said, but a structure array. For example if you had 10 versions of data all with different names you'd have 10*9/2 = 45 separate if blocks to compare all possible pairs. If you had one variable, data, that was a structure array, then you don't need to compare all combinations pair-by-pair, but you could do a nested loop to make all comparisons:
for k1 = 1 : length(data)
    for k2 = 1 : k1-1
        if isequal(data(k1).gamma, data(k2).gamma)
            % They're equal
        else
            % They're not equal.
        end
    end
end
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