{"action":"closed","issue":{"url":"https://api.github.com/repos/lmcinnes/hdbscan/issues/31","repository_url":"https://api.github.com/repos/lmcinnes/hdbscan","labels_url":"https://api.github.com/repos/lmcinnes/hdbscan/issues/31/labels{/name}","comments_url":"https://api.github.com/repos/lmcinnes/hdbscan/issues/31/comments","events_url":"https://api.github.com/repos/lmcinnes/hdbscan/issues/31/events","html_url":"https://github.com/lmcinnes/hdbscan/issues/31","id":144717814,"number":31,"title":"Add something about parameter selection to the notebooks?","user":{"login":"gwerbin","id":5758789,"avatar_url":"https://avatars.githubusercontent.com/u/5758789?v=3","gravatar_id":"","url":"https://api.github.com/users/gwerbin","html_url":"https://github.com/gwerbin","followers_url":"https://api.github.com/users/gwerbin/followers","following_url":"https://api.github.com/users/gwerbin/following{/other_user}","gists_url":"https://api.github.com/users/gwerbin/gists{/gist_id}","starred_url":"https://api.github.com/users/gwerbin/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gwerbin/subscriptions","organizations_url":"https://api.github.com/users/gwerbin/orgs","repos_url":"https://api.github.com/users/gwerbin/repos","events_url":"https://api.github.com/users/gwerbin/events{/privacy}","received_events_url":"https://api.github.com/users/gwerbin/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":4,"created_at":"2016-03-30T20:55:24Z","updated_at":"2016-04-17T04:31:46Z","closed_at":"2016-04-17T04:31:46Z","body":"I really appreciate the work you've done with the \"How HDBSCAN Works\" notebook, but they don't really touch on the issue of parameter selection. You do mention at the end of the clustering comparison notebook that HDBSCAN is not that sensitive to the choice of `min_samples`, but that isn't much to go on.\r\n\r\nIf I'm not mistaken, the `alpha` and `min_samples` parameters are both \"inherited\" from robust single linkage clustering. But Chaudhuri and Dasgupta are not terribly forthcoming about what their `alpha` parameter actually does, apart from stating that \"we'd like `alpha` as small as possible\" (pg. 6, [\"Rates of convergence for the cluster tree\"](http://cseweb.ucsd.edu/~dasgupta/papers/tree.pdf)). So I'm left scratching my head as to how to select these.\r\n\r\nDo you think you'd be able to talk about how to intelligently choose the core size (`min_samples`) and that `alpha` parameter? You also mention sensible defaults, but you don't mention what makes them sensible.\r\n\r\nUnfortunately, I don't have access to Campello, et al.'s original paper, so if it's explained there I won't be able to see it. Dr. Campello mentions on his site that unformatted copies of his work are available, and I'm planning on reaching out to him for that purpose if I can't get access through my old university. But I still think it would be a great addition to these already very helpful notebooks (and it can't hurt the adoption of HDBSCAN itself as a \"sensible default\" for clustering applications)."}}