how to make a code for distributing n different things among r groups such that each group get atleast certain amount?

if I have 7 machines and I want to distribute them in 3 groups with all possible combinations such that each group has atleast 2 machines.how can I code this?

Answer 1

[Guillaume]

machines = 1:7;
groupcount = 3;
minmachinepergroup = 2;

minmachines = minmachinepergroup * groupcount;
assert(numel(machines) >= minmachines, 'Not enough to fill the minimum in each goup');

rmachines = machines(randperm(numel(machines))); %randomise the machines
groupdest = [repmat(1:groupcount, 1, minmachinepergroup), randi(groupcount, 1, numel(machines) - minmachines)];  %distribute first the minimum per group, then randomise
groups = accumarray(groupdest(:), rmachines, [], @(v) {v});  %distribute the machines into the groups

[summyia qamar]

how can I change this?

C = zeros(3^7,7);
t = 0;
for k = 0:(3^7)-1
  s = dec2base(k,3,7);
  if length(unique(s))==3
    t = t+1;
    C(t,:) = s-‘0’+1;
  end
end
C = C(1:t,:);