{"action":"created","issue":{"url":"https://api.github.com/repos/Rdatatable/data.table/issues/1224","labels_url":"https://api.github.com/repos/Rdatatable/data.table/issues/1224/labels{/name}","comments_url":"https://api.github.com/repos/Rdatatable/data.table/issues/1224/comments","events_url":"https://api.github.com/repos/Rdatatable/data.table/issues/1224/events","html_url":"https://github.com/Rdatatable/data.table/issues/1224","id":95158296,"number":1224,"title":"uniqueN could supports list input","user":{"login":"jangorecki","id":3627377,"avatar_url":"https://avatars.githubusercontent.com/u/3627377?v=3","gravatar_id":"","url":"https://api.github.com/users/jangorecki","html_url":"https://github.com/jangorecki","followers_url":"https://api.github.com/users/jangorecki/followers","following_url":"https://api.github.com/users/jangorecki/following{/other_user}","gists_url":"https://api.github.com/users/jangorecki/gists{/gist_id}","starred_url":"https://api.github.com/users/jangorecki/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jangorecki/subscriptions","organizations_url":"https://api.github.com/users/jangorecki/orgs","repos_url":"https://api.github.com/users/jangorecki/repos","events_url":"https://api.github.com/users/jangorecki/events{/privacy}","received_events_url":"https://api.github.com/users/jangorecki/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":4,"created_at":"2015-07-15T10:22:59Z","updated_at":"2015-07-16T19:40:01Z","closed_at":null,"body":"And not just lists but any type which is not supported by `uniqueN` could simply redirects to `length(unique(.))`.\r\n```r\r\nlibrary(data.table)\r\nd1 <- data.table(a = 1:4, l = list(list(letters[1:2]),list(Sys.time()),list(1:10),list(letters[1:2])))\r\nd1[,length(unique(l))]\r\n# [1] 3\r\nd1[,uniqueN(l)]\r\n#Error in uniqueN(l) : \r\n#  x must be an atomic vector or data.frames/data.tables\r\n```\r\nLooks pretty easy to do, I will try to make PR for that."},"comment":{"url":"https://api.github.com/repos/Rdatatable/data.table/issues/comments/122065126","html_url":"https://github.com/Rdatatable/data.table/issues/1224#issuecomment-122065126","issue_url":"https://api.github.com/repos/Rdatatable/data.table/issues/1224","id":122065126,"user":{"login":"arunsrinivasan","id":3102045,"avatar_url":"https://avatars.githubusercontent.com/u/3102045?v=3","gravatar_id":"","url":"https://api.github.com/users/arunsrinivasan","html_url":"https://github.com/arunsrinivasan","followers_url":"https://api.github.com/users/arunsrinivasan/followers","following_url":"https://api.github.com/users/arunsrinivasan/following{/other_user}","gists_url":"https://api.github.com/users/arunsrinivasan/gists{/gist_id}","starred_url":"https://api.github.com/users/arunsrinivasan/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/arunsrinivasan/subscriptions","organizations_url":"https://api.github.com/users/arunsrinivasan/orgs","repos_url":"https://api.github.com/users/arunsrinivasan/repos","events_url":"https://api.github.com/users/arunsrinivasan/events{/privacy}","received_events_url":"https://api.github.com/users/arunsrinivasan/received_events","type":"User","site_admin":false},"created_at":"2015-07-16T19:40:01Z","updated_at":"2015-07-16T19:40:01Z","body":"Maybe for single column case we can already use the fix you've provided, and take care of `.SD` / `data.table` cases later. Will merge asap. Thanks @jangorecki."}}