create pr

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

@@ -80,13 +80,12 @@ final class DataFrameStatFunctions private[sql](df: DataFrame) {
    * @see [[DataFrameStatsFunctions.approxQuantile(col:Str* approxQuantile]] for
    *     detailed description.
    *
-   * Note that rows containing any null or NaN values values will be removed before
-   * calculation.
+   * Note that rows containing any null or NaN values will be removed before calculation.
    * @param cols the names of the numerical columns
    * @param probabilities a list of quantile probabilities
    *   Each number must belong to [0, 1].
    *   For example 0 is the minimum, 0.5 is the median, 1 is the maximum.
-   * @param relativeError The relative target precision to achieve (>= 0).
+   * @param relativeError The relative target precision to achieve (greater or equal to 0).
    *   If set to zero, the exact quantiles are computed, which could be very expensive.
    *   Note that values greater than 1 are accepted but give the same result as 1.
    * @return the approximate quantiles at the given probabilities of each column
@@ -112,7 +111,7 @@ final class DataFrameStatFunctions private[sql](df: DataFrame) {
       probabilities: List[Double],
       relativeError: Double): java.util.List[java.util.List[Double]] = {
     approxQuantile(cols.toArray, probabilities.toArray, relativeError)
-        .map(_.toList.asJava).toList.asJava
+      .map(_.toList.asJava).toList.asJava
   }
 
   /**

sql/core/src/main/scala/org/apache/spark/sql/execution/stat/StatFunctions.scala

@@ -49,7 +49,7 @@ object StatFunctions extends Logging {
    * @param probabilities a list of quantile probabilities
    *   Each number must belong to [0, 1].
    *   For example 0 is the minimum, 0.5 is the median, 1 is the maximum.
-   * @param relativeError The relative target precision to achieve (>= 0).
+   * @param relativeError The relative target precision to achieve (greater or equal 0).
    *   If set to zero, the exact quantiles are computed, which could be very expensive.
    *   Note that values greater than 1 are accepted but give the same result as 1.
    *
@@ -60,6 +60,8 @@ object StatFunctions extends Logging {
       cols: Seq[String],
       probabilities: Seq[Double],
       relativeError: Double): Seq[Seq[Double]] = {
+    require(relativeError >= 0,
+      s"Relative Error must be non-negative but got $relativeError")
     val columns: Seq[Column] = cols.map { colName =>
       val field = df.schema(colName)
       require(field.dataType.isInstanceOf[NumericType],

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

@@ -25,7 +25,7 @@ import org.apache.spark.internal.Logging
 import org.apache.spark.sql.execution.stat.StatFunctions
 import org.apache.spark.sql.functions.col
 import org.apache.spark.sql.test.SharedSQLContext
-import org.apache.spark.sql.types.DoubleType
+import org.apache.spark.sql.types.{DoubleType, StructField, StructType}
 
 class DataFrameStatSuite extends QueryTest with SharedSQLContext {
   import testImplicits._
@@ -159,16 +159,53 @@ class DataFrameStatSuite extends QueryTest with SharedSQLContext {
       assert(math.abs(md1 - 2 * q1 * n) < error_double)
       assert(math.abs(md2 - 2 * q2 * n) < error_double)
     }
-    // test approxQuantile on NaN values
-    val dfNaN = Seq(Double.NaN, 1.0, Double.NaN, Double.NaN).toDF("input")
-    val resNaN = dfNaN.stat.approxQuantile("input", Array(q1, q2), epsilons.head)
+
+    // test relativeError greater than 1 return the same result as 1
+    val Array(single1_1) = df.stat.approxQuantile("singles", Array(q1), 1.0)
+    val Array(s1_1, s2_1) = df.stat.approxQuantile("singles", Array(q1, q2), 1.0)
+    val Array(Array(ms1_1, ms2_1), Array(md1_1, md2_1)) =
+      df.stat.approxQuantile(Array("singles", "doubles"), Array(q1, q2), 1.0)
+    for (epsilon <- Seq(2.0, 100.0)) {
+      val Array(single1) = df.stat.approxQuantile("singles", Array(q1), epsilon)
+      val Array(s1, s2) = df.stat.approxQuantile("singles", Array(q1, q2), epsilon)
+      val Array(Array(ms1, ms2), Array(md1, md2)) =
+        df.stat.approxQuantile(Array("singles", "doubles"), Array(q1, q2), epsilon)
+      assert(single1_1 === single1)
+      assert(s1_1 === s1)
+      assert(s2_1 === s2)
+      assert(ms1_1 === ms1)
+      assert(ms2_1 === ms2)
+      assert(md1_1 === md1)
+      assert(md2_1 === md2)
+    }
+
+    // quantile should be in the range [0.0, 1.0]
+    val e: IllegalArgumentException = intercept[IllegalArgumentException] {
+      df.stat.approxQuantile(Array("singles", "doubles"), Array(q1, q2, -0.1), epsilons.head)
+    }
+    assert(e.getMessage.contains("quantile should be in the range [0.0, 1.0]"))
+
+    // relativeError should be non-negative
+    val e2: IllegalArgumentException = intercept[IllegalArgumentException] {
+      df.stat.approxQuantile(Array("singles", "doubles"), Array(q1, q2), -1.0)
+    }
+    assert(e2.getMessage.contains("Relative Error must be non-negative"))
+
+    // test approxQuantile on NaN and null values
+    val rows = spark.sparkContext.parallelize(Seq(Row(Double.NaN, 1.0), Row(1.0, 1.0),
+      Row(-1.0, Double.NaN), Row(Double.NaN, Double.NaN), Row(null, null), Row(null, 1.0),
+      Row(-1.0, null), Row(Double.NaN, null)))
+    val schema = StructType(Seq(StructField("input1", DoubleType, nullable = true),
+      StructField("input2", DoubleType, nullable = true)))
+    val dfNaN = spark.createDataFrame(rows, schema)
+    val resNaN = dfNaN.stat.approxQuantile("input1", Array(q1, q2), epsilons.head)
     assert(resNaN.count(_.isNaN) === 0)
-    // test approxQuantile on multi-column NaN values
-    val dfNaN2 = Seq((Double.NaN, 1.0), (1.0, 1.0), (-1.0, Double.NaN), (Double.NaN, Double.NaN))
-      .toDF("input1", "input2")
-    val resNaN2 = dfNaN2.stat.approxQuantile(Array("input1", "input2"),
+    assert(resNaN.count(_ == null) === 0)
+
+    val resNaN2 = dfNaN.stat.approxQuantile(Array("input1", "input2"),
       Array(q1, q2), epsilons.head)
     assert(resNaN2.flatten.count(_.isNaN) === 0)
+    assert(resNaN2.flatten.count(_ == null) === 0)
   }
 
   test("crosstab") {