combine vectors

% data generation
for i = 1:10000
   j = mod(i, 100);
   k = floor((i-1) / 100)+1;
   eval(['proj_', sprintf('%03d', j), '_', sprintf('%03d', k), '=randn(1, randi(100, 1));']);
end

% binding
varNames = who;
loc = ~cellfun('isempty', regexp(varNames, '^proj_\d{3}_\d{3}$', 'once'));
varNames = varNames(loc, :);
varCell = cell(size(varNames, 1), 1);
for i = 1:size(varNames, 1)
    varCell{i} = eval(varNames{i});
end
maxLength = max(cellfun(@numel, varCell));
biningMat = zeros(size(varNames, 1), maxLength);
for i = 1:size(varNames, 1)
    biningMat(1:numel(varCell{i}), i) = varCell{i};
end