DEV: Created scala function that trains a forest

and passes back to python context (#237)

src/main/scala/au/csiro/variantspark/api/GetRFModel.scala

@@ -0,0 +1,26 @@
+package au.csiro.variantspark.api
+
+import au.csiro.variantspark.algo.{
+  RandomForest,
+  RandomForestModel,
+  RandomForestParams
+}
+import au.csiro.variantspark.input.{FeatureSource, LabelSource}
+
+/** Passes a trained random forest model back to the python wrapper
+  */
+object RFModelTrainer {
+  def trainModel(
+      featureSource: FeatureSource,
+      labelSource: LabelSource,
+      params: RandomForestParams,
+      nTrees: Int,
+      rfBatchSize: Int
+  ): RandomForestModel = {
+    val labels = labelSource.getLabels(featureSource.sampleNames)
+    lazy val inputData = featureSource.features.zipWithIndex.cache()
+    val rf = new RandomForest(params)
+    val rfTrained = rf.batchTrain(inputData, labels, nTrees, rfBatchSize)
+    rfTrained
+  }
+}