Example of a specific data partitioner

spark-custom-partitioner.scala

class AlphabetPartitioner extends Partitioner {
  def numPartitions = 26
  def getPartition(key: Any): Int = key match {
    case s: String => s(0).toUpper - 'A'
  }
  override def equals(other: Any): Boolean = other.isInstanceOf[AlphabetPartitioner]
  override def hashCode: Int = 0
}