2d:null 2e:["$","title",null,{"children":"Random group generator | Nacho Caballero | Observable"}] 33:T598,It turns out that generating all the possible groupings of n people into k groups for as many rounds as possible while minimizing repeat pairings in each round is a notoriously [difficult](https://stackoverflow.com/questions/24332311/what-algorithm-can-generate-round-robin-pairings-for-rounds-with-more-than-two) [problem](https://stackoverflow.com/questions/28965908/algorithm-for-generating-anti-gray-on-demand-combinations-of-k-elements-from-n) similar to the [Social golfer problem](https://en.wikipedia.org/wiki/Social_golfer_problem) or [Kirkman's Schoolgirl problem](https://mathworld.wolfram.com/KirkmansSchoolgirlProblem.html) (NP hard?). Another way to describe it is a round-robin tournament with k groups and more than two players per group. After many attempts, I ended up with this approach (it's kind of a hack, but it works): - I try to generate a groupset for each round (`numRounds`) but I often get fewer because I don't allow repeat groups (it tries `maxTries` times to avoid an infinite loop) - Each groupset contains k groups, one for each teacher (the groups are different sizes when n is not divisible by k) - I order the groupsets to minimize the number of repeat pairs (maximize the number of new pairings per round). - I use a pseudo-random generator to ensure I always get the same result (as long as I don't change the seed). - I use the checkboxes to ignore students that decide to skip a round/day.34:[] 31:{"id":"f8ba9ace78edabb4","slug":"random-group-generator","title":"Random group generator","thumbnail":"b0d2fbfbb147eacb7ffe0f2efb59b6b0b505c240e7193d002b14c41dded1089e","access_level":"public","create_time":"$D2023-08-27T07:52:11.627Z","update_time":"$D2023-09-24T15:09:26.280Z","view_time":null,"first_public_time":"$D2023-08-27T07:52:11.627Z","has_unpublished_edits":null,"fork":false,"stars":2,"starred":false,"owner":{"type":"team","id":"70a88bc30ad137e1","login":"nachocab","name":"Nacho Caballero","avatar_url":"https://avatars-next.observableusercontent.com/225a321e3612e41b73bcd50e0ee2d6ca386939be025d3a87d1611323abe2c59d","tier":"starter_2024"},"version":670,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"fad4469b7022b4d5","login":"nachocab","name":"Nacho Caballero","avatar_url":"https://avatars-next.observableusercontent.com/225a321e3612e41b73bcd50e0ee2d6ca386939be025d3a87d1611323abe2c59d","tier":null}],"members":[{"type":"individual","id":"fad4469b7022b4d5","login":"nachocab","name":"Nacho Caballero","avatar_url":"https://avatars-next.observableusercontent.com/225a321e3612e41b73bcd50e0ee2d6ca386939be025d3a87d1611323abe2c59d","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"title":"Random group generator","cells":[{"id":0,"value":"# Random group generator","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":517,"value":"viewof participatingStudents = {\n const form = Inputs.checkbox(studentNames, {\n // label: \"Estudiantes que participan\",\n value: studentNames\n //value: studentNames.filter(d => d != \"Larissa\")\n });\n const scope = DOM.uid().id;\n form.classList.add(scope);\n form.append(htl.html`