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[jvm-packages] Objectives starting with rank: are never classification (#2837)

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Training a model with the experimental rank:ndcg objective incorrectly
returns a Classification model. Adjust the classification check to
not recognize rank:* objectives as classification.

While writing tests for isClassificationTask also turned up that
obj_type -> regression was incorrectly identified as a classification
task so the function was slightly adjusted to pass the new tests.
This commit is contained in:
ebernhardson 2017-10-30 09:36:03 -07:00 committed by Sergei Lebedev
parent 91af8f7106
commit 46f2b820f1
2 changed files with 26 additions and 2 deletions
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4
jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala
View File

@ -194,8 +194,8 @@ object XGBoost extends Serializable {
val objective = params.getOrElse("objective", params.getOrElse("obj_type", null))
objective != null && {
val objStr = objective.toString
objStr == "classification" || (!objStr.startsWith("reg:") && objStr != "count:poisson" &&
objStr != "rank:pairwise")
objStr != "regression" && !objStr.startsWith("reg:") && objStr != "count:poisson" &&
!objStr.startsWith("rank:")
}
}

24
jvm-packages/xgboost4j-spark/src/test/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostGeneralSuite.scala
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@ -389,4 +389,28 @@ class XGBoostGeneralSuite extends FunSuite with PerTest {
assert(eval.eval(xgBoostModel.booster.predict(testSetDMatrix, outPutMargin = true),
testSetDMatrix) < 0.1)
}
test("isClassificationTask correctly classifies supported objectives") {
import org.scalatest.prop.TableDrivenPropertyChecks._
val objectives = Table(
("isClassificationTask", "params"),
(true, Map("obj_type" -> "classification")),
(false, Map("obj_type" -> "regression")),
(false, Map("objective" -> "rank:ndcg")),
(false, Map("objective" -> "rank:pairwise")),
(false, Map("objective" -> "rank:map")),
(false, Map("objective" -> "count:poisson")),
(true, Map("objective" -> "binary:logistic")),
(true, Map("objective" -> "binary:logitraw")),
(true, Map("objective" -> "multi:softmax")),
(true, Map("objective" -> "multi:softprob")),
(false, Map("objective" -> "reg:linear")),
(false, Map("objective" -> "reg:logistic")),
(false, Map("objective" -> "reg:gamma")),
(false, Map("objective" -> "reg:tweedie")))
forAll (objectives) { (isClassificationTask: Boolean, params: Map[String, String]) =>
assert(XGBoost.isClassificationTask(params) == isClassificationTask)
}
}
}