{"action":"created","issue":{"url":"https://api.github.com/repos/blaze/dask/issues/610","labels_url":"https://api.github.com/repos/blaze/dask/issues/610/labels{/name}","comments_url":"https://api.github.com/repos/blaze/dask/issues/610/comments","events_url":"https://api.github.com/repos/blaze/dask/issues/610/events","html_url":"https://github.com/blaze/dask/pull/610","id":102169586,"number":610,"title":"Allow dd.concat to handle known divisions","user":{"login":"sinhrks","id":1696302,"avatar_url":"https://avatars.githubusercontent.com/u/1696302?v=3","gravatar_id":"","url":"https://api.github.com/users/sinhrks","html_url":"https://github.com/sinhrks","followers_url":"https://api.github.com/users/sinhrks/followers","following_url":"https://api.github.com/users/sinhrks/following{/other_user}","gists_url":"https://api.github.com/users/sinhrks/gists{/gist_id}","starred_url":"https://api.github.com/users/sinhrks/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sinhrks/subscriptions","organizations_url":"https://api.github.com/users/sinhrks/orgs","repos_url":"https://api.github.com/users/sinhrks/repos","events_url":"https://api.github.com/users/sinhrks/events{/privacy}","received_events_url":"https://api.github.com/users/sinhrks/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-08-20T15:45:14Z","updated_at":"2015-08-20T20:16:49Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/blaze/dask/pulls/610","html_url":"https://github.com/blaze/dask/pull/610","diff_url":"https://github.com/blaze/dask/pull/610.diff","patch_url":"https://github.com/blaze/dask/pull/610.patch"},"body":"Allow ``dask.dataframe.concat`` to concat ``DataFrame`` with known divisions. In this case, not concatenated to last, but concatenate every divisions each by each.\r\n\r\nAnother option is concatenate to last resetting all divisions to ``None``, but I think it is not very useful.\r\n\r\n```\r\nimport pandas as pd\r\nimport dask.dataframe as dd\r\ndf1 = pd.DataFrame({'a': [1, 2, 3, 4], 'b': [1, 2 ,3 ,4]})\r\ndf2 = pd.DataFrame({'a': [5, 6, 7, 8], 'b': [5, 6 ,7 ,8]})\r\nddf1 = dd.from_pandas(df1, 2)\r\nddf2 = dd.from_pandas(df2, 2)\r\n\r\nddf1.divisions\r\n# (0, 2, 3)\r\n\r\ndd.concat([ddf1, ddf2]).compute()\r\n#    a  b\r\n# 0  1  1\r\n# 1  2  2\r\n# 0  5  5\r\n# 1  6  6\r\n# 2  3  3\r\n# 3  4  4\r\n# 2  7  7\r\n# 3  8  8\r\n```"},"comment":{"url":"https://api.github.com/repos/blaze/dask/issues/comments/133158711","html_url":"https://github.com/blaze/dask/pull/610#issuecomment-133158711","issue_url":"https://api.github.com/repos/blaze/dask/issues/610","id":133158711,"user":{"login":"mrocklin","id":306380,"avatar_url":"https://avatars.githubusercontent.com/u/306380?v=3","gravatar_id":"","url":"https://api.github.com/users/mrocklin","html_url":"https://github.com/mrocklin","followers_url":"https://api.github.com/users/mrocklin/followers","following_url":"https://api.github.com/users/mrocklin/following{/other_user}","gists_url":"https://api.github.com/users/mrocklin/gists{/gist_id}","starred_url":"https://api.github.com/users/mrocklin/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mrocklin/subscriptions","organizations_url":"https://api.github.com/users/mrocklin/orgs","repos_url":"https://api.github.com/users/mrocklin/repos","events_url":"https://api.github.com/users/mrocklin/events{/privacy}","received_events_url":"https://api.github.com/users/mrocklin/received_events","type":"User","site_admin":false},"created_at":"2015-08-20T20:16:49Z","updated_at":"2015-08-20T20:16:49Z","body":"This looks good to me"}}