[SPARK-3516] [mllib] DecisionTree: Add minInstancesPerNode, minInfoGain params to example and Python API

Added minInstancesPerNode, minInfoGain params to:
* DecisionTreeRunner.scala example
* Python API (tree.py)

Also:
* Fixed typo in tree suite test "do not choose split that does not satisfy min instance per node requirements"
* small style fixes

CC: mengxr

Author: qiping.lqp <qiping.lqp@alibaba-inc.com>
Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>
Author: chouqin <liqiping1991@gmail.com>

Closes #2349 from jkbradley/chouqin-dt-preprune and squashes the following commits:

61b2e72 [Joseph K. Bradley] Added max of 10GB for maxMemoryInMB in Strategy.
a95e7c8 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into chouqin-dt-preprune
95c479d [Joseph K. Bradley] * Fixed typo in tree suite test "do not choose split that does not satisfy min instance per node requirements" * small style fixes
e2628b6 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into chouqin-dt-preprune
19b01af [Joseph K. Bradley] Merge remote-tracking branch 'chouqin/dt-preprune' into chouqin-dt-preprune
f1d11d1 [chouqin] fix typo
c7ebaf1 [chouqin] fix typo
39f9b60 [chouqin] change edge `minInstancesPerNode` to 2 and add one more test
c6e2dfc [Joseph K. Bradley] Added minInstancesPerNode and minInfoGain parameters to DecisionTreeRunner.scala and to Python API in tree.py
0278a11 [chouqin] remove `noSplit` and set `Predict` private to tree
d593ec7 [chouqin] fix docs and change minInstancesPerNode to 1
efcc736 [qiping.lqp] fix bug
10b8012 [qiping.lqp] fix style
6728fad [qiping.lqp] minor fix: remove empty lines
bb465ca [qiping.lqp] Merge branch 'master' of https://github.com/apache/spark into dt-preprune
cadd569 [qiping.lqp] add api docs
46b891f [qiping.lqp] fix bug
e72c7e4 [qiping.lqp] add comments
845c6fa [qiping.lqp] fix style
f195e83 [qiping.lqp] fix style
987cbf4 [qiping.lqp] fix bug
ff34845 [qiping.lqp] separate calculation of predict of node from calculation of info gain
ac42378 [qiping.lqp] add min info gain and min instances per node parameters in decision tree

1 files changed, 12 insertions, 1 deletions

diff --git a/examples/src/main/scala/org/apache/spark/examples/mllib/DecisionTreeRunner.scala b/examples/src/main/scala/org/apache/spark/examples/mllib/DecisionTreeRunner.scala
index 72c3ab475b..4683e6eb96 100644
--- a/examples/src/main/scala/org/apache/spark/examples/mllib/DecisionTreeRunner.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/mllib/DecisionTreeRunner.scala
@@ -55,6 +55,8 @@ object DecisionTreeRunner {
       maxDepth: Int = 5,
       impurity: ImpurityType = Gini,
       maxBins: Int = 32,
+      minInstancesPerNode: Int = 1,
+      minInfoGain: Double = 0.0,
       fracTest: Double = 0.2)
 
   def main(args: Array[String]) {
@@ -75,6 +77,13 @@ object DecisionTreeRunner {
       opt[Int]("maxBins")
         .text(s"max number of bins, default: ${defaultParams.maxBins}")
         .action((x, c) => c.copy(maxBins = x))
+      opt[Int]("minInstancesPerNode")
+        .text(s"min number of instances required at child nodes to create the parent split," +
+        s" default: ${defaultParams.minInstancesPerNode}")
+        .action((x, c) => c.copy(minInstancesPerNode = x))
+      opt[Double]("minInfoGain")
+        .text(s"min info gain required to create a split, default: ${defaultParams.minInfoGain}")
+        .action((x, c) => c.copy(minInfoGain = x))
       opt[Double]("fracTest")
         .text(s"fraction of data to hold out for testing, default: ${defaultParams.fracTest}")
         .action((x, c) => c.copy(fracTest = x))
@@ -179,7 +188,9 @@ object DecisionTreeRunner {
           impurity = impurityCalculator,
           maxDepth = params.maxDepth,
           maxBins = params.maxBins,
-          numClassesForClassification = numClasses)
+          numClassesForClassification = numClasses,
+          minInstancesPerNode = params.minInstancesPerNode,
+          minInfoGain = params.minInfoGain)
     val model = DecisionTree.train(training, strategy)
 
     println(model)