org.apache.spark.util.collection.Utils.scala Maven / Gradle / Ivy
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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,
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package org.apache.spark.util.collection
import scala.collection.JavaConverters._
import com.google.common.collect.{Ordering => GuavaOrdering}
/**
* Utility functions for collections.
*/
private[spark] object Utils {
/**
* Returns the first K elements from the input as defined by the specified implicit Ordering[T]
* and maintains the ordering.
*/
def takeOrdered[T](input: Iterator[T], num: Int)(implicit ord: Ordering[T]): Iterator[T] = {
val ordering = new GuavaOrdering[T] {
override def compare(l: T, r: T): Int = ord.compare(l, r)
}
ordering.leastOf(input.asJava, num).iterator.asScala
}
}