skeletal framework

Signed-off-by: Manish Amde <manish9ue@gmail.com>

mllib/src/main/scala/org/apache/spark/mllib/classification/ClassificationTree.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.classification
+
+class ClassificationTree {
+
+}

mllib/src/main/scala/org/apache/spark/mllib/regression/RegressionTree.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.regression
+
+class RegressionTree {
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/DecisionTree.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.mllib.tree
+
+import org.apache.spark.rdd.RDD
+import org.apache.spark.mllib.regression.LabeledPoint
+import org.apache.spark.mllib.tree.model.{Split, Bin, DecisionTreeModel}
+
+
+class DecisionTree(val strategy : Strategy) {
+
+  def train(input : RDD[LabeledPoint]) : DecisionTreeModel = {
+
+    //Cache input RDD for speedup during multiple passes
+    input.cache()
+
+    //TODO: Find all splits and bins using quantiles including support for categorical features, single-pass
+    val (splits, bins) = DecisionTree.find_splits_bins(input, strategy)
+
+    //TODO: Level-wise training of tree and obtain Decision Tree model
+
+
+    return new DecisionTreeModel()
+  }
+
+}
+
+object DecisionTree {
+  def find_splits_bins(input : RDD[LabeledPoint], strategy : Strategy) : (Array[Array[Split]], Array[Array[Bin]]) = {
+    val numSplits = strategy.numSplits
+    //TODO: Justify this calculation
+    val requiredSamples : Long = numSplits*numSplits
+    val count : Long = input.count()
+    val numSamples : Long = if (requiredSamples < count) requiredSamples else count
+    val numFeatures = input.take(1)(0).features.length
+    (Array.ofDim[Split](numFeatures,numSplits),Array.ofDim[Bin](numFeatures,numSplits))
+  }
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/README.md

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+This package contains the default implementation of the decision tree algorithm.
+
+The decision tree algorithm supports:
++ information loss calculation with entropy and gini for classification and variance for regression
++ node model pruning
++ printing to dot files
++ unit tests
+
+#Performance testing
+
+#Future Extensions
+
++ Random forests
++ Boosting
++ Extremely randomized trees

mllib/src/main/scala/org/apache/spark/mllib/tree/Strategy.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree
+
+import org.apache.spark.mllib.tree.impurity.Impurity
+
+class Strategy (
+                val kind : String,
+                val impurity : Impurity,
+                val maxDepth : Int,
+                val numSplits : Int,
+                val quantileCalculationStrategy : String = "sampleAndSort") {
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/impurity/Entropy.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.impurity
+
+object Entropy extends Impurity {
+
+   def log2(x: Double) = scala.math.log(x) / scala.math.log(2)
+
+   def calculate(c0: Double, c1: Double): Double = {
+     if (c0 == 0 || c1 == 0) {
+       0
+     } else {
+       val total = c0 + c1
+       val f0 = c0 / total
+       val f1 = c1 / total
+       -(f0 * log2(f0)) - (f1 * log2(f1))
+     }
+   }
+
+ }

mllib/src/main/scala/org/apache/spark/mllib/tree/impurity/Gini.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.impurity
+
+object Gini extends Impurity {
+
+   def calculate(c0 : Double, c1 : Double): Double = {
+     val total = c0 + c1
+     val f0 = c0 / total
+     val f1 = c1 / total
+     1 - f0*f0 - f1*f1
+   }
+
+ }

mllib/src/main/scala/org/apache/spark/mllib/tree/impurity/Impurity.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.impurity
+
+trait Impurity {
+
+  def calculate(c0 : Double, c1 : Double): Double
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/impurity/Variance.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.impurity
+
+import javax.naming.OperationNotSupportedException
+
+object Variance extends Impurity {
+   def calculate(c0: Double, c1: Double): Double = throw new OperationNotSupportedException("Variance.calculate")
+ }

mllib/src/main/scala/org/apache/spark/mllib/tree/model/Bin.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.model
+
+case class Bin(kind : String, lowSplit : Split, highSplit : Split) {
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/model/DecisionTreeModel.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.model
+
+class DecisionTreeModel {
+
+}

mllib/src/main/scala/org/apache/spark/mllib/tree/model/Split.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.model
+
+case class Split(
+            val feature: Int,
+            val threshold : Double,
+            val kind : String) {
+
+}
+
+class dummyLowSplit(kind : String) extends Split(Int.MinValue, Double.MinValue, kind)
+
+class dummyHighSplit(kind : String) extends Split(Int.MaxValue, Double.MaxValue, kind)
+