[SPARK-7150] SparkContext.range() and SQLContext.range()

This PR is based on #6081, thanks adrian-wang.

Closes #6081

Author: Daoyuan Wang <daoyuan.wang@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #6230 from davies/range and squashes the following commits:

d3ce5fe [Davies Liu] add tests
789eda5 [Davies Liu] add range() in Python
4590208 [Davies Liu] Merge commit 'refs/pull/6081/head' of github.com:apache/spark into range
cbf5200 [Daoyuan Wang] let's add python support in a separate PR
f45e3b2 [Daoyuan Wang] remove redundant toLong
617da76 [Daoyuan Wang] fix safe marge for corner cases
867c417 [Daoyuan Wang] fix
13dbe84 [Daoyuan Wang] update
bd998ba [Daoyuan Wang] update comments
d3a0c1b [Daoyuan Wang] add range api()

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -697,6 +697,78 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
     new ParallelCollectionRDD[T](this, seq, numSlices, Map[Int, Seq[String]]())
   }
 
+  /**
+   * Creates a new RDD[Long] containing elements from `start` to `end`(exclusive), increased by
+   * `step` every element.
+   *
+   * @note if we need to cache this RDD, we should make sure each partition does not exceed limit.
+   *
+   * @param start the start value.
+   * @param end the end value.
+   * @param step the incremental step
+   * @param numSlices the partition number of the new RDD.
+   * @return
+   */
+  def range(
+      start: Long,
+      end: Long,
+      step: Long = 1,
+      numSlices: Int = defaultParallelism): RDD[Long] = withScope {
+    assertNotStopped()
+    // when step is 0, range will run infinitely
+    require(step != 0, "step cannot be 0")
+    val numElements: BigInt = {
+      val safeStart = BigInt(start)
+      val safeEnd = BigInt(end)
+      if ((safeEnd - safeStart) % step == 0 || safeEnd > safeStart ^ step > 0) {
+        (safeEnd - safeStart) / step
+      } else {
+        // the remainder has the same sign with range, could add 1 more
+        (safeEnd - safeStart) / step + 1
+      }
+    }
+    parallelize(0 until numSlices, numSlices).mapPartitionsWithIndex((i, _) => {
+      val partitionStart = (i * numElements) / numSlices * step + start
+      val partitionEnd = (((i + 1) * numElements) / numSlices) * step + start
+      def getSafeMargin(bi: BigInt): Long =
+        if (bi.isValidLong) {
+          bi.toLong
+        } else if (bi > 0) {
+          Long.MaxValue
+        } else {
+          Long.MinValue
+        }
+      val safePartitionStart = getSafeMargin(partitionStart)
+      val safePartitionEnd = getSafeMargin(partitionEnd)
+
+      new Iterator[Long] {
+        private[this] var number: Long = safePartitionStart
+        private[this] var overflow: Boolean = false
+
+        override def hasNext =
+          if (!overflow) {
+            if (step > 0) {
+              number < safePartitionEnd
+            } else {
+              number > safePartitionEnd
+            }
+          } else false
+
+        override def next() = {
+          val ret = number
+          number += step
+          if (number < ret ^ step < 0) {
+            // we have Long.MaxValue + Long.MaxValue < Long.MaxValue
+            // and Long.MinValue + Long.MinValue > Long.MinValue, so iff the step causes a step
+            // back, we are pretty sure that we have an overflow.
+            overflow = true
+          }
+          ret
+        }
+      }
+    })
+  }
+
   /** Distribute a local Scala collection to form an RDD.
    *
    * This method is identical to `parallelize`.

python/pyspark/context.py

@@ -319,6 +319,22 @@ class SparkContext(object):
         with SparkContext._lock:
             SparkContext._active_spark_context = None
 
+    def range(self, start, end, step=1, numSlices=None):
+        """
+        Create a new RDD of int containing elements from `start` to `end`
+        (exclusive), increased by `step` every element.
+
+        :param start: the start value
+        :param end: the end value (exclusive)
+        :param step: the incremental step (default: 1)
+        :param numSlices: the number of partitions of the new RDD
+        :return: An RDD of int
+
+        >>> sc.range(1, 7, 2).collect()
+        [1, 3, 5]
+        """
+        return self.parallelize(xrange(start, end, step), numSlices)
+
     def parallelize(self, c, numSlices=None):
         """
         Distribute a local Python collection to form an RDD. Using xrange

python/pyspark/sql/context.py

@@ -122,6 +122,26 @@ class SQLContext(object):
         """Returns a :class:`UDFRegistration` for UDF registration."""
         return UDFRegistration(self)
 
+    def range(self, start, end, step=1, numPartitions=None):
+        """
+        Create a :class:`DataFrame` with single LongType column named `id`,
+        containing elements in a range from `start` to `end` (exclusive) with
+        step value `step`.
+
+        :param start: the start value
+        :param end: the end value (exclusive)
+        :param step: the incremental step (default: 1)
+        :param numPartitions: the number of partitions of the DataFrame
+        :return: A new DataFrame
+
+        >>> sqlContext.range(1, 7, 2).collect()
+        [Row(id=1), Row(id=3), Row(id=5)]
+        """
+        if numPartitions is None:
+            numPartitions = self._sc.defaultParallelism
+        jdf = self._ssql_ctx.range(int(start), int(end), int(step), int(numPartitions))
+        return DataFrame(jdf, self)
+
     @ignore_unicode_prefix
     def registerFunction(self, name, f, returnType=StringType()):
         """Registers a lambda function as a UDF so it can be used in SQL statements.

python/pyspark/sql/tests.py

@@ -117,6 +117,11 @@ class SQLTests(ReusedPySparkTestCase):
         ReusedPySparkTestCase.tearDownClass()
         shutil.rmtree(cls.tempdir.name, ignore_errors=True)
 
+    def test_range(self):
+        self.assertEqual(self.sqlCtx.range(1, 1).count(), 0)
+        self.assertEqual(self.sqlCtx.range(1, 0, -1).count(), 1)
+        self.assertEqual(self.sqlCtx.range(0, 1 << 40, 1 << 39).count(), 2)
+
     def test_explode(self):
         from pyspark.sql.functions import explode
         d = [Row(a=1, intlist=[1, 2, 3], mapfield={"a": "b"})]

python/pyspark/tests.py

@@ -444,6 +444,11 @@ class AddFileTests(PySparkTestCase):
 
 class RDDTests(ReusedPySparkTestCase):
 
+    def test_range(self):
+        self.assertEqual(self.sc.range(1, 1).count(), 0)
+        self.assertEqual(self.sc.range(1, 0, -1).count(), 1)
+        self.assertEqual(self.sc.range(0, 1 << 40, 1 << 39).count(), 2)
+
     def test_id(self):
         rdd = self.sc.parallelize(range(10))
         id = rdd.id()

sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala

@@ -684,6 +684,37 @@ class SQLContext(@transient val sparkContext: SparkContext)
     catalog.unregisterTable(Seq(tableName))
   }
 
+  /**
+   * :: Experimental ::
+   * Creates a [[DataFrame]] with a single [[LongType]] column named `id`, containing elements
+   * in an range from `start` to `end`(exclusive) with step value 1.
+   *
+   * @since 1.4.0
+   * @group dataframe
+   */
+  @Experimental
+  def range(start: Long, end: Long): DataFrame = {
+    createDataFrame(
+      sparkContext.range(start, end).map(Row(_)),
+      StructType(StructField("id", LongType, nullable = false) :: Nil))
+  }
+
+  /**
+   * :: Experimental ::
+   * Creates a [[DataFrame]] with a single [[LongType]] column named `id`, containing elements
+   * in an range from `start` to `end`(exclusive) with an step value, with partition number
+   * specified.
+   *
+   * @since 1.4.0
+   * @group dataframe
+   */
+  @Experimental
+  def range(start: Long, end: Long, step: Long, numPartitions: Int): DataFrame = {
+    createDataFrame(
+      sparkContext.range(start, end, step, numPartitions).map(Row(_)),
+      StructType(StructField("id", LongType, nullable = false) :: Nil))
+  }
+
   /**
    * Executes a SQL query using Spark, returning the result as a [[DataFrame]]. The dialect that is
    * used for SQL parsing can be configured with 'spark.sql.dialect'.

sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala

@@ -532,4 +532,44 @@ class DataFrameSuite extends QueryTest {
     val p = df.logicalPlan.asInstanceOf[Project].child.asInstanceOf[Project]
     assert(!p.child.isInstanceOf[Project])
   }
+
+  test("SPARK-7150 range api") {
+    // numSlice is greater than length
+    val res1 = TestSQLContext.range(0, 10, 1, 15).select("id")
+    assert(res1.count == 10)
+    assert(res1.agg(sum("id")).as("sumid").collect() === Seq(Row(45)))
+
+    val res2 = TestSQLContext.range(3, 15, 3, 2).select("id")
+    assert(res2.count == 4)
+    assert(res2.agg(sum("id")).as("sumid").collect() === Seq(Row(30)))
+
+    val res3 = TestSQLContext.range(1, -2).select("id")
+    assert(res3.count == 0)
+
+    // start is positive, end is negative, step is negative
+    val res4 = TestSQLContext.range(1, -2, -2, 6).select("id")
+    assert(res4.count == 2)
+    assert(res4.agg(sum("id")).as("sumid").collect() === Seq(Row(0)))
+
+    // start, end, step are negative
+    val res5 = TestSQLContext.range(-3, -8, -2, 1).select("id")
+    assert(res5.count == 3)
+    assert(res5.agg(sum("id")).as("sumid").collect() === Seq(Row(-15)))
+
+    // start, end are negative, step is positive
+    val res6 = TestSQLContext.range(-8, -4, 2, 1).select("id")
+    assert(res6.count == 2)
+    assert(res6.agg(sum("id")).as("sumid").collect() === Seq(Row(-14)))
+
+    val res7 = TestSQLContext.range(-10, -9, -20, 1).select("id")
+    assert(res7.count == 0)
+
+    val res8 = TestSQLContext.range(Long.MinValue, Long.MaxValue, Long.MaxValue, 100).select("id")
+    assert(res8.count == 3)
+    assert(res8.agg(sum("id")).as("sumid").collect() === Seq(Row(-3)))
+
+    val res9 = TestSQLContext.range(Long.MaxValue, Long.MinValue, Long.MinValue, 100).select("id")
+    assert(res9.count == 2)
+    assert(res9.agg(sum("id")).as("sumid").collect() === Seq(Row(Long.MaxValue - 1)))
+  }
 }