function resultTable = groupIt(fixedVars, dataTable, aggregationFunction)
% groupIt Groups data in a table based on fixedVars and applies aggregationFunction to numeric data.
%
%   resultTable = groupIt(fixedVars, dataTable, aggregationFunction)
%
%   Inputs:
%       fixedVars           - Cell array of variable names to group by
%       dataTable           - Input MATLAB table
%       aggregationFunction - Function handle (e.g., @mean, @min, @max)
%
%   Output:
%       resultTable         - Grouped and aggregated table

[G, groupKeys] = findgroups(dataTable(:, fixedVars));
varNames = dataTable.Properties.VariableNames;
nVars = numel(varNames);
aggData = cell(height(groupKeys), nVars);
groupCount = zeros(height(groupKeys), 1);

for i = 1:height(groupKeys)
    idx = (G == i);
    groupCount(i) = sum(idx);
    for j = 1:nVars
        colData = dataTable.(varNames{j});
        if isnumeric(colData)
            if any(idx)
                aggData{i, j} = aggregationFunction(colData(idx));
            else
                aggData{i, j} = NaN;
            end
        else
            if iscell(colData)
                nonEmptyIdx = find(idx & ~cellfun(@isempty, colData), 1);
                if ~isempty(nonEmptyIdx)
                    aggData{i, j} = colData{nonEmptyIdx};
                else
                    aggData{i, j} = [];
                end
            else
                nonEmptyIdx = find(idx, 1);
                if ~isempty(nonEmptyIdx)
                    aggData{i, j} = colData(nonEmptyIdx);
                else
                    aggData{i, j} = [];
                end
            end
        end
    end
end

resultTable = cell2table(aggData, 'VariableNames', varNames);
resultTable.nRows = groupCount;
end