{"action":"created","issue":{"url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/11176","repository_url":"https://api.github.com/repos/scikit-learn/scikit-learn","labels_url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/11176/labels{/name}","comments_url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/11176/comments","events_url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/11176/events","html_url":"https://github.com/scikit-learn/scikit-learn/pull/11176","id":328153060,"node_id":"MDExOlB1bGxSZXF1ZXN0MTkxNzY1MDI4","number":11176,"title":"[MRG] Normalization fix for gbm ensemble feature importances","user":{"login":"gforsyth","id":3596999,"node_id":"MDQ6VXNlcjM1OTY5OTk=","avatar_url":"https://avatars0.githubusercontent.com/u/3596999?v=4","gravatar_id":"","url":"https://api.github.com/users/gforsyth","html_url":"https://github.com/gforsyth","followers_url":"https://api.github.com/users/gforsyth/followers","following_url":"https://api.github.com/users/gforsyth/following{/other_user}","gists_url":"https://api.github.com/users/gforsyth/gists{/gist_id}","starred_url":"https://api.github.com/users/gforsyth/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gforsyth/subscriptions","organizations_url":"https://api.github.com/users/gforsyth/orgs","repos_url":"https://api.github.com/users/gforsyth/repos","events_url":"https://api.github.com/users/gforsyth/events{/privacy}","received_events_url":"https://api.github.com/users/gforsyth/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2018-05-31T14:05:57Z","updated_at":"2018-06-01T13:35:45Z","closed_at":null,"author_association":"NONE","pull_request":{"url":"https://api.github.com/repos/scikit-learn/scikit-learn/pulls/11176","html_url":"https://github.com/scikit-learn/scikit-learn/pull/11176","diff_url":"https://github.com/scikit-learn/scikit-learn/pull/11176.diff","patch_url":"https://github.com/scikit-learn/scikit-learn/pull/11176.patch"},"body":"\r\n\r\n#### Reference Issues/PRs\r\n<!--\r\nExample: Fixes #1234. See also #3456.\r\nPlease use keywords (e.g., Fixes) to create link to the issues or pull requests\r\nyou resolved, so that they will automatically be closed when your pull request\r\nis merged. See https://github.com/blog/1506-closing-issues-via-pull-requests\r\n-->\r\n\r\n\r\n#### What does this implement/fix? Explain your changes.\r\nThis makes a small change to the ``BaseDecisionTree`` and\r\n``DecisionTreeRegressor``, adding a ``normalize_feature_importances`` ``kwarg``\r\nthat defaults to ``True`` (matching current behavior) but is set to ``False``\r\nfor GBMs.\r\n\r\nTree-level feature importances are calculated as the proportional reduction of\r\nthat tree's root node entropy (see [_tree.pyx](https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/tree/_tree.pyx#L1056)) and ensemble-level importances are\r\naveraged across trees.\r\n\r\nBecause the feature importances are (currently, by default) normalized and then\r\naveraged, feature importances from later stages are overweighted.\r\n\r\nGBMs now defer the normalization step until after the per-tree importances have\r\nbeen calculated (for the ``DecisionTreeRegressor`` used in\r\n``ensemble.gradient_boosting.BaseGradientBoosting``).\r\n\r\n\r\n#### Any other comments?\r\nh/t to Joel Danke for spotting this and writing up the issue.\r\n\r\n"},"comment":{"url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/comments/393882465","html_url":"https://github.com/scikit-learn/scikit-learn/pull/11176#issuecomment-393882465","issue_url":"https://api.github.com/repos/scikit-learn/scikit-learn/issues/11176","id":393882465,"node_id":"MDEyOklzc3VlQ29tbWVudDM5Mzg4MjQ2NQ==","user":{"login":"gforsyth","id":3596999,"node_id":"MDQ6VXNlcjM1OTY5OTk=","avatar_url":"https://avatars0.githubusercontent.com/u/3596999?v=4","gravatar_id":"","url":"https://api.github.com/users/gforsyth","html_url":"https://github.com/gforsyth","followers_url":"https://api.github.com/users/gforsyth/followers","following_url":"https://api.github.com/users/gforsyth/following{/other_user}","gists_url":"https://api.github.com/users/gforsyth/gists{/gist_id}","starred_url":"https://api.github.com/users/gforsyth/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gforsyth/subscriptions","organizations_url":"https://api.github.com/users/gforsyth/orgs","repos_url":"https://api.github.com/users/gforsyth/repos","events_url":"https://api.github.com/users/gforsyth/events{/privacy}","received_events_url":"https://api.github.com/users/gforsyth/received_events","type":"User","site_admin":false},"created_at":"2018-06-01T13:35:45Z","updated_at":"2018-06-01T13:35:45Z","author_association":"NONE","body":"Thanks for looking it over!"}}
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