com.alpine.model.pack.util.TransformerUtil.scala Maven / Gradle / Ivy

Go to download
package com.alpine.model.pack.util

/**
 * Utility functions that Transformers may need.
 */
object TransformerUtil {

  /**
   * WARNING: Mutates input.
   *
   * Puts the contents of row into the tempArray argument.
   * The two arguments must be the same length.
   *
   * Uses [[anyToDouble()]] for double conversion.
   * @param row contains the values to be read.
   * @param tempArray the array to be written to.
   * @return reference to tempArray, filled with the contents of the row.
   */
  def fillRowToDoubleArray(row: Seq[Any], tempArray: Array[Double]) = {
    var i = 0
    while (i < tempArray.length) {
      tempArray(i) = anyToDouble(row(i))
      i += 1
    }
    tempArray
  }

  /**
   * Converts input of type Any to Double.
   * Does this by casting to java.lang.Number,
   * and then taking the double value.
   *
   * Will return Double.NaN in the case of bad input.
   *
   * @param a input to be converted to Double.
   * @return Double representation of the number, or Double.NaN if impossible.
   */
  def anyToDouble(a: Any): Double = {
    try {
      a.asInstanceOf[Number].doubleValue()
    }
    catch {
      case _: NullPointerException => Double.NaN
      case _: ClassCastException => Double.NaN
    }
  }

  def toJavaDoubleSeq(doubles: Seq[Double]): Seq[java.lang.Double] = {
    doubles.map(d => d.asInstanceOf[java.lang.Double])
  }

  def javaDoubleSeqToArray(doubles: Seq[java.lang.Double]): Array[Double] = {
    doubles.map(d => d.doubleValue()).toArray
  }
}

/**
 * Dresses the row argument in a Seq[Double].
 * Elements that can't be casted to java.lang.Number will
 * be represented by Double.NaN.
 * @param row Seq[Any] to be dressed as Seq[Double]
 */
case class CastedDoubleSeq(row: Seq[Any]) extends Seq[Double] {

  override def length: Int = row.length

  override def iterator: Iterator[Double] = {
    new Iterator[Double] {
      val rowIterator = row.iterator
      override def hasNext: Boolean = rowIterator.hasNext

      override def next(): Double = TransformerUtil.anyToDouble(rowIterator.next())
    }
  }

  override def apply(idx: Int): Double = TransformerUtil.anyToDouble(row(idx))

}