GenerateGroupVariables.m

function [GroupByTrial, GroupByChannel ] = ...
    GenerateGroupVariables(Data, TrialNames, TrialLengths)


    
if length(TrialNames) == 3
    LengthTrialOne = TrialLengths(1); LengthTrialTwo = TrialLengths(2);
    LengthTrialThree = TrialLengths(3);
    GroupByTrial = cell(length(Data), 1);
    [GroupByTrial{1:...
        (3 * TrialLengths(1) ) } ] = deal(TrialNames{1});
    [GroupByTrial{(3 * TrialLengths(1) + 1 ) : ...
        (3 * TrialLengths(1) + 3 * TrialLengths(2) ) } ] = deal(TrialNames{2});
    [GroupByTrial{ ( 3 * TrialLengths(1) + 3 * TrialLengths(2) + 1 ) : ...
        (3 * TrialLengths(1) + 3 * TrialLengths(2) + 3 * TrialLengths(3)) } ] = ...
        deal(TrialNames{3});
    
    [GroupByChannel{1:LengthTrialOne}] = deal('Roll');
    [GroupByChannel{(LengthTrialOne+1):(2 * LengthTrialOne) }] = deal('Pitch');
    [GroupByChannel{(LengthTrialOne * 2 + 1):(3 * LengthTrialOne) }] = deal('Yaw');
    [GroupByChannel{(3 * LengthTrialOne + 1) : ...
        (3 * LengthTrialOne + LengthTrialTwo) } ] = deal('Roll');
    [GroupByChannel{ (3 * LengthTrialOne + LengthTrialTwo + 1) : ...
        ( 3 * LengthTrialOne + 2 * LengthTrialTwo) }] = deal('Pitch');
    [GroupByChannel{ ( 3 * LengthTrialOne + 2 * LengthTrialTwo + 1) : ...
        ( 3 * LengthTrialOne + 3 * LengthTrialTwo) }] = deal('Yaw');
    [GroupByChannel{ ( 3 * LengthTrialOne + 3 * LengthTrialTwo + 1) : ...
        ( 3 * LengthTrialOne + 3 * LengthTrialTwo + LengthTrialThree ) } ] = ...
        deal('Roll');
    [GroupByChannel{ (3*LengthTrialOne + ...
        3*LengthTrialTwo + LengthTrialThree + 1) : ...
        (3*LengthTrialOne + 3*LengthTrialTwo + 2*LengthTrialThree) } ] = ...
        deal('Pitch');
    [GroupByChannel{ ( 3*LengthTrialOne + 3*LengthTrialTwo + ...
        2*LengthTrialThree + 1) : ...
        (3*LengthTrialOne + 3*LengthTrialTwo + 3*LengthTrialThree) } ] = ...
        deal('Yaw');
    
elseif length(TrialNames) == 2
    GroupByTrial = cell(length(Data), 1);
    LengthTrialOne = TrialLengths(1); LengthTrialTwo = TrialLengths(2);
    
    [GroupByTrial{1:...
        (3 * TrialLengths(1) ) } ] = deal(TrialNames{1});
    [GroupByTrial{(3 * TrialLengths(1) + 1 ) : ...
        (3 * TrialLengths(1) + 3 * TrialLengths(2) ) } ] = deal(TrialNames{2});
    [GroupByChannel{1:LengthTrialOne}] = deal('Roll');
    [GroupByChannel{(LengthTrialOne+1):(2 * LengthTrialOne) }] = deal('Pitch');
    [GroupByChannel{(LengthTrialOne * 2 + 1):(3 * LengthTrialOne) }] = deal('Yaw');
    [GroupByChannel{(3 * LengthTrialOne + 1) : ...
        (3 * LengthTrialOne + LengthTrialTwo) } ] = deal('Roll');
    [GroupByChannel{ (3 * LengthTrialOne + LengthTrialTwo + 1) : ...
        ( 3 * LengthTrialOne + 2 * LengthTrialTwo) }] = deal('Pitch');
    [GroupByChannel{ ( 3 * LengthTrialOne + 2 * LengthTrialTwo + 1) : ...
        ( 3 * LengthTrialOne + 3 * LengthTrialTwo) }] = deal('Yaw');
    
elseif length(TrialNames) == 1
    GroupByTrial = cell(length(Data), 1); 
    LengthTrialOne = TrialLengths(1);
    [GroupByTrial{1:end}] = deal(TrialNames{1}); 
      
    [GroupByChannel{1:LengthTrialOne}] = deal('Roll');
    [GroupByChannel{(LengthTrialOne+1):(2 * LengthTrialOne) }] = deal('Pitch');
    [GroupByChannel{(LengthTrialOne * 2 + 1):(3 * LengthTrialOne) }] = deal('Yaw');
        
else error('Error! Number of trials must be 0, 1, or 2.')
end