{"action":"created","issue":{"url":"https://api.github.com/repos/apache/spark/issues/19433","repository_url":"https://api.github.com/repos/apache/spark","labels_url":"https://api.github.com/repos/apache/spark/issues/19433/labels{/name}","comments_url":"https://api.github.com/repos/apache/spark/issues/19433/comments","events_url":"https://api.github.com/repos/apache/spark/issues/19433/events","html_url":"https://github.com/apache/spark/pull/19433","id":262951215,"node_id":"MDExOlB1bGxSZXF1ZXN0MTQ0NzkxNDM4","number":19433,"title":"[SPARK-3162] [MLlib] Add local tree training for decision tree regressors","user":{"login":"smurching","id":2358483,"node_id":"MDQ6VXNlcjIzNTg0ODM=","avatar_url":"https://avatars1.githubusercontent.com/u/2358483?v=4","gravatar_id":"","url":"https://api.github.com/users/smurching","html_url":"https://github.com/smurching","followers_url":"https://api.github.com/users/smurching/followers","following_url":"https://api.github.com/users/smurching/following{/other_user}","gists_url":"https://api.github.com/users/smurching/gists{/gist_id}","starred_url":"https://api.github.com/users/smurching/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/smurching/subscriptions","organizations_url":"https://api.github.com/users/smurching/orgs","repos_url":"https://api.github.com/users/smurching/repos","events_url":"https://api.github.com/users/smurching/events{/privacy}","received_events_url":"https://api.github.com/users/smurching/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":34,"created_at":"2017-10-04T22:30:57Z","updated_at":"2018-10-24T14:19:03Z","closed_at":null,"author_association":"CONTRIBUTOR","pull_request":{"url":"https://api.github.com/repos/apache/spark/pulls/19433","html_url":"https://github.com/apache/spark/pull/19433","diff_url":"https://github.com/apache/spark/pull/19433.diff","patch_url":"https://github.com/apache/spark/pull/19433.patch"},"body":"## What changes were proposed in this pull request?\r\n\r\n### Overview\r\nThis PR adds local tree training for decision tree regressors as a first step for addressing [SPARK-3162](https://issues.apache.org/jira/browse/SPARK-3162): train decision trees locally when possible.\r\n\r\nSee [this design doc](https://docs.google.com/document/d/1baU5KeorrmLpC4EZoqLuG-E8sUJqmdELLbr8o6wdbVM/edit) (in particular the [local tree training section](https://docs.google.com/document/d/1baU5KeorrmLpC4EZoqLuG-E8sUJqmdELLbr8o6wdbVM/edit#heading=h.eiteb09wxsjf)) for detailed discussion of the proposed changes.\r\n\r\nDistributed training logic has been refactored but only minimally modified; the local tree training implementation leverages existing distributed training logic for computing impurities and splits. This shared logic has been refactored into `...Utils` objects (e.g. `SplitUtils.scala`, `ImpurityUtils.scala`). \r\n\r\n### How to Review\r\n\r\nEach commit in this PR adds non-overlapping functionality, so the PR can be reviewed commit-by-commit.\r\n\r\nChanges introduced by each commit:\r\n1. Adds new data structures for local tree training (`FeatureVector`, `TrainingInfo`)\r\n2. Adds shared utility methods for computing splits/impurities (`SplitUtils`, `ImpurityUtils`, `AggUpdateUtils`), largely copied from existing distributed training code in `RandomForest.scala`.\r\n3. Unit tests for split/impurity utility methods (`TreeSplitUtilsSuite`)\r\n4. Updates distributed training code in `RandomForest.scala` to depend on the utility methods introduced in 2.\r\n5. Adds local tree training logic (`LocalDecisionTree`) \r\n6. Local tree unit/integration tests (`LocalTreeUnitSuite`, `LocalTreeIntegrationSuite`)\r\n\r\n## How was this patch tested?\r\nNo existing tests were modified. The following new tests were added (also described above):\r\n* Unit tests for new data structures specific to local tree training (`LocalTreeDataSuite`, `LocalTreeUtilsSuite`)\r\n* Unit tests for impurity/split utility methods (`TreeSplitUtilsSuite`)\r\n* Unit tests for local tree training logic (`LocalTreeUnitSuite`)\r\n* Integration tests verifying that local & distributed tree training produce the same trees (`LocalTreeIntegrationSuite`)"},"comment":{"url":"https://api.github.com/repos/apache/spark/issues/comments/432676812","html_url":"https://github.com/apache/spark/pull/19433#issuecomment-432676812","issue_url":"https://api.github.com/repos/apache/spark/issues/19433","id":432676812,"node_id":"MDEyOklzc3VlQ29tbWVudDQzMjY3NjgxMg==","user":{"login":"SparkQA","id":8108735,"node_id":"MDQ6VXNlcjgxMDg3MzU=","avatar_url":"https://avatars1.githubusercontent.com/u/8108735?v=4","gravatar_id":"","url":"https://api.github.com/users/SparkQA","html_url":"https://github.com/SparkQA","followers_url":"https://api.github.com/users/SparkQA/followers","following_url":"https://api.github.com/users/SparkQA/following{/other_user}","gists_url":"https://api.github.com/users/SparkQA/gists{/gist_id}","starred_url":"https://api.github.com/users/SparkQA/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/SparkQA/subscriptions","organizations_url":"https://api.github.com/users/SparkQA/orgs","repos_url":"https://api.github.com/users/SparkQA/repos","events_url":"https://api.github.com/users/SparkQA/events{/privacy}","received_events_url":"https://api.github.com/users/SparkQA/received_events","type":"User","site_admin":false},"created_at":"2018-10-24T14:19:03Z","updated_at":"2018-10-24T14:19:03Z","author_association":"NONE","body":"**[Test build #97977 has started](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/97977/testReport)** for PR 19433 at commit [`d86dd18`](https://github.com/apache/spark/commit/d86dd18e47451c2e4463c68db441f92a898ac765)."}}
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