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From: chiwanpark <git@git.apache.org>
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Subject: [GitHub] flink pull request: [FLINK-3919][flink-ml] Distributed Linear Alge...
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Message-Id: <20160530122636.88777DFC8C@git1-us-west.apache.org>
Date: Mon, 30 May 2016 12:26:36 +0000 (UTC)
archived-at: Mon, 30 May 2016 12:26:42 -0000

Github user chiwanpark commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1996#discussion_r65064961
  
    --- Diff: flink-libraries/flink-ml/src/main/scala/org/apache/flink/ml/math/distributed/DistributedRowMatrix.scala ---
    @@ -0,0 +1,167 @@
    +/*
    + * 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.flink.ml.math.distributed
    +
    +import java.lang
    +
    +import breeze.linalg.{CSCMatrix => BreezeSparseMatrix, Matrix => BreezeMatrix, Vector => BreezeVector}
    +import org.apache.flink.api.common.functions.RichGroupReduceFunction
    +import org.apache.flink.api.common.typeinfo.TypeInformation
    +import org.apache.flink.api.scala._
    +import org.apache.flink.ml.math.{Matrix => FlinkMatrix, _}
    +import org.apache.flink.util.Collector
    +import org.apache.flink.ml.math.Breeze._
    +import scala.collection.JavaConversions._
    +
    +/**
    +  *
    +  * @param numRowsOpt If None, will be calculated from the DataSet.
    +  * @param numColsOpt If None, will be calculated from the DataSet.
    +  */
    +class DistributedRowMatrix(data: DataSet[IndexedRow],
    +                           numRowsOpt: Option[Int] = None,
    +                           numColsOpt: Option[Int] = None)
    +    extends DistributedMatrix {
    +
    +  lazy val getNumRows: Int = numRowsOpt match {
    +    case Some(rows) => rows
    +    case None => data.count().toInt
    +  }
    +
    +  lazy val getNumCols: Int = numColsOpt match {
    +    case Some(cols) => cols
    +    case None => calcCols
    +  }
    +
    +  val getRowData = data
    +
    +  private def calcCols: Int =
    +    data.first(1).collect().headOption match {
    +      case Some(vector) => vector.values.size
    +      case None => 0
    +    }
    +
    +  /**
    +    * Collects the data in the form of a sequence of coordinates associated with their values.
    +    * @return
    +    */
    +  def toCOO: Seq[(Int, Int, Double)] = {
    +
    +    val localRows = data.collect()
    +
    +    for (IndexedRow(rowIndex, vector) <- localRows;
    +    (columnIndex, value) <- vector) yield (rowIndex, columnIndex, value)
    +  }
    +
    +  /**
    +    * Collects the data in the form of a SparseMatrix
    +    * @return
    +    */
    +  def toLocalSparseMatrix: SparseMatrix = {
    +    val localMatrix = SparseMatrix.fromCOO(this.getNumRows, this.getNumCols, this.toCOO)
    +    require(localMatrix.numRows == this.getNumRows)
    +    require(localMatrix.numCols == this.getNumCols)
    +    localMatrix
    +  }
    +
    +  //TODO: convert to dense representation on the distributed matrix and collect it afterward
    +  def toLocalDenseMatrix: DenseMatrix = this.toLocalSparseMatrix.toDenseMatrix
    +
    +  def byRowOperation(
    +      fun: (Vector, Vector) => Vector, other: DistributedRowMatrix): DistributedRowMatrix = {
    +    val otherData = other.getRowData
    +    require(this.getNumCols == other.getNumCols)
    +    require(this.getNumRows == other.getNumRows)
    +
    +    val ev1: TypeInformation[Int] = TypeInformation.of(classOf[Int])
    +
    +    val result = this.data
    +      .fullOuterJoin(otherData)
    +      .where(_.rowIndex)
    +      .equalTo(_.rowIndex)(ev1)(
    --- End diff --
    
    Key selector function creates copying keys overhead. please change this to like following:
    
    ```scala
    val result = this.data
      .fullOuterJoin(otherData)
      .where("rowIndex")
      .equalTo("rowIndex") {
        (left: IndexedRow, right: IndexedRow) => ...
      }
    ```


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