From 3a9d82cc9e85accb5c1577cf4718aa44c8d5038c Mon Sep 17 00:00:00 2001
From: Andrew Ash <andrew@andrewash.com>
Date: Thu, 6 Feb 2014 22:38:36 -0800
Subject: [PATCH] Merge pull request #506 from ash211/intersection. Closes
#506.
SPARK-1062 Add rdd.intersection(otherRdd) method
Author: Andrew Ash <andrew@andrewash.com>
== Merge branch commits ==
commit 5d9982b171b9572649e9828f37ef0b43f0242912
Author: Andrew Ash <andrew@andrewash.com>
Date: Thu Feb 6 18:11:45 2014 -0800
Minor fixes
- style: (v,null) => (v, null)
- mention the shuffle in Javadoc
commit b86d02f14e810902719cef893cf6bfa18ff9acb0
Author: Andrew Ash <andrew@andrewash.com>
Date: Sun Feb 2 13:17:40 2014 -0800
Overload .intersection() for numPartitions and custom Partitioner
commit bcaa34911fcc6bb5bc5e4f9fe46d1df73cb71c09
Author: Andrew Ash <andrew@andrewash.com>
Date: Sun Feb 2 13:05:40 2014 -0800
Better naming of parameters in intersection's filter
commit b10a6af2d793ec6e9a06c798007fac3f6b860d89
Author: Andrew Ash <andrew@andrewash.com>
Date: Sat Jan 25 23:06:26 2014 -0800
Follow spark code format conventions of tab => 2 spaces
commit 965256e4304cca514bb36a1a36087711dec535ec
Author: Andrew Ash <andrew@andrewash.com>
Date: Fri Jan 24 00:28:01 2014 -0800
Add rdd.intersection(otherRdd) method
---
.../main/scala/org/apache/spark/rdd/RDD.scala | 37 +++++++++++++++++++
.../scala/org/apache/spark/rdd/RDDSuite.scala | 23 +++++++++++-
2 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/core/src/main/scala/org/apache/spark/rdd/RDD.scala b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
index 033d334079..8010bb68e3 100644
--- a/core/src/main/scala/org/apache/spark/rdd/RDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
@@ -393,6 +393,43 @@ abstract class RDD[T: ClassTag](
*/
def ++(other: RDD[T]): RDD[T] = this.union(other)
+ /**
+ * Return the intersection of this RDD and another one. The output will not contain any duplicate
+ * elements, even if the input RDDs did.
+ *
+ * Note that this method performs a shuffle internally.
+ */
+ def intersection(other: RDD[T]): RDD[T] =
+ this.map(v => (v, null)).cogroup(other.map(v => (v, null)))
+ .filter { case (_, (leftGroup, rightGroup)) => leftGroup.nonEmpty && rightGroup.nonEmpty }
+ .keys
+
+ /**
+ * Return the intersection of this RDD and another one. The output will not contain any duplicate
+ * elements, even if the input RDDs did.
+ *
+ * Note that this method performs a shuffle internally.
+ *
+ * @param partitioner Partitioner to use for the resulting RDD
+ */
+ def intersection(other: RDD[T], partitioner: Partitioner): RDD[T] =
+ this.map(v => (v, null)).cogroup(other.map(v => (v, null)), partitioner)
+ .filter { case (_, (leftGroup, rightGroup)) => leftGroup.nonEmpty && rightGroup.nonEmpty }
+ .keys
+
+ /**
+ * Return the intersection of this RDD and another one. The output will not contain any duplicate
+ * elements, even if the input RDDs did. Performs a hash partition across the cluster
+ *
+ * Note that this method performs a shuffle internally.
+ *
+ * @param numPartitions How many partitions to use in the resulting RDD
+ */
+ def intersection(other: RDD[T], numPartitions: Int): RDD[T] =
+ this.map(v => (v, null)).cogroup(other.map(v => (v, null)), new HashPartitioner(numPartitions))
+ .filter { case (_, (leftGroup, rightGroup)) => leftGroup.nonEmpty && rightGroup.nonEmpty }
+ .keys
+
/**
* Return an RDD created by coalescing all elements within each partition into an array.
*/
diff --git a/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala b/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala
index 223ebec5fa..879c4e5f17 100644
--- a/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala
+++ b/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala
@@ -373,8 +373,8 @@ class RDDSuite extends FunSuite with SharedSparkContext {
val prng42 = new Random(42)
val prng43 = new Random(43)
Array(1, 2, 3, 4, 5, 6).filter{i =>
- if (i < 4) 0 == prng42.nextInt(3)
- else 0 == prng43.nextInt(3)}
+ if (i < 4) 0 == prng42.nextInt(3)
+ else 0 == prng43.nextInt(3)}
}
assert(sample.size === checkSample.size)
for (i <- 0 until sample.size) assert(sample(i) === checkSample(i))
@@ -506,4 +506,23 @@ class RDDSuite extends FunSuite with SharedSparkContext {
sc.runJob(sc.parallelize(1 to 10, 2), {iter: Iterator[Int] => iter.size}, Seq(0, 1, 2), false)
}
}
+
+ test("intersection") {
+ val all = sc.parallelize(1 to 10)
+ val evens = sc.parallelize(2 to 10 by 2)
+ val intersection = Array(2, 4, 6, 8, 10)
+
+ // intersection is commutative
+ assert(all.intersection(evens).collect.sorted === intersection)
+ assert(evens.intersection(all).collect.sorted === intersection)
+ }
+
+ test("intersection strips duplicates in an input") {
+ val a = sc.parallelize(Seq(1,2,3,3))
+ val b = sc.parallelize(Seq(1,1,2,3))
+ val intersection = Array(1,2,3)
+
+ assert(a.intersection(b).collect.sorted === intersection)
+ assert(b.intersection(a).collect.sorted === intersection)
+ }
}
--
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