diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index bbf465aca8d4da8c50c13eae3c2f6d30d0086e44..177fc196e08349705cf450bf1eb8544ca45424ab 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -18,6 +18,7 @@
"""
A collections of builtin functions
"""
+import math
import sys
if sys.version < "3":
@@ -143,7 +144,7 @@ _binary_mathfunctions = {
'atan2': 'Returns the angle theta from the conversion of rectangular coordinates (x, y) to' +
'polar coordinates (r, theta).',
'hypot': 'Computes `sqrt(a^2^ + b^2^)` without intermediate overflow or underflow.',
- 'pow': 'Returns the value of the first argument raised to the power of the second argument.'
+ 'pow': 'Returns the value of the first argument raised to the power of the second argument.',
}
_window_functions = {
@@ -403,6 +404,21 @@ def when(condition, value):
return Column(jc)
+@since(1.4)
+def log(col, base=math.e):
+ """Returns the first argument-based logarithm of the second argument.
+
+ >>> df.select(log(df.age, 10.0).alias('ten')).map(lambda l: str(l.ten)[:7]).collect()
+ ['0.30102', '0.69897']
+
+ >>> df.select(log(df.age).alias('e')).map(lambda l: str(l.e)[:7]).collect()
+ ['0.69314', '1.60943']
+ """
+ sc = SparkContext._active_spark_context
+ jc = sc._jvm.functions.log(base, _to_java_column(col))
+ return Column(jc)
+
+
@since(1.4)
def lag(col, count=1, default=None):
"""
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala
index 97b123ec2f6d9147ae84b754554deff306eb3d66..13b2bb05f528021b8928ee56b3b99c31e45ec56b 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala
@@ -112,6 +112,7 @@ object FunctionRegistry {
expression[Expm1]("expm1"),
expression[Floor]("floor"),
expression[Hypot]("hypot"),
+ expression[Logarithm]("log"),
expression[Log]("ln"),
expression[Log10]("log10"),
expression[Log1p]("log1p"),
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
index 42c596b5b31ab89a0335d1757cbc4ca27be36bf2..67cb0b508ca9efc5f32a25cfd4ff4aa4d3c936f4 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
@@ -255,3 +255,23 @@ case class Pow(left: Expression, right: Expression)
"""
}
}
+
+case class Logarithm(left: Expression, right: Expression)
+ extends BinaryMathExpression((c1, c2) => math.log(c2) / math.log(c1), "LOG") {
+ def this(child: Expression) = {
+ this(EulerNumber(), child)
+ }
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
+ val logCode = if (left.isInstanceOf[EulerNumber]) {
+ defineCodeGen(ctx, ev, (c1, c2) => s"java.lang.Math.log($c2)")
+ } else {
+ defineCodeGen(ctx, ev, (c1, c2) => s"java.lang.Math.log($c2) / java.lang.Math.log($c1)")
+ }
+ logCode + s"""
+ if (Double.valueOf(${ev.primitive}).isNaN()) {
+ ${ev.isNull} = true;
+ }
+ """
+ }
+}
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
index 864c954ee82cb752dde615998648357660decda5..0050ad3fe8302debb7651eed4099bef6c32da88e 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/MathFunctionsSuite.scala
@@ -204,4 +204,22 @@ class MathFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper {
testBinary(Atan2, math.atan2)
}
+ test("binary log") {
+ val f = (c1: Double, c2: Double) => math.log(c2) / math.log(c1)
+ val domain = (1 to 20).map(v => (v * 0.1, v * 0.2))
+
+ domain.foreach { case (v1, v2) =>
+ checkEvaluation(Logarithm(Literal(v1), Literal(v2)), f(v1 + 0.0, v2 + 0.0), EmptyRow)
+ checkEvaluation(Logarithm(Literal(v2), Literal(v1)), f(v2 + 0.0, v1 + 0.0), EmptyRow)
+ checkEvaluation(new Logarithm(Literal(v1)), f(math.E, v1 + 0.0), EmptyRow)
+ }
+ checkEvaluation(
+ Logarithm(Literal.create(null, DoubleType), Literal(1.0)),
+ null,
+ create_row(null))
+ checkEvaluation(
+ Logarithm(Literal(1.0), Literal.create(null, DoubleType)),
+ null,
+ create_row(null))
+ }
}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
index c5b77724aae17336698ccbc0b3e603a8968936a7..dff0932c450a84d2b1c5b4084fa38f26c93a269c 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/functions.scala
@@ -1083,6 +1083,22 @@ object functions {
*/
def log(columnName: String): Column = log(Column(columnName))
+ /**
+ * Returns the first argument-base logarithm of the second argument.
+ *
+ * @group math_funcs
+ * @since 1.4.0
+ */
+ def log(base: Double, a: Column): Column = Logarithm(lit(base).expr, a.expr)
+
+ /**
+ * Returns the first argument-base logarithm of the second argument.
+ *
+ * @group math_funcs
+ * @since 1.4.0
+ */
+ def log(base: Double, columnName: String): Column = log(base, Column(columnName))
+
/**
* Computes the logarithm of the given value in base 10.
*
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/MathExpressionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/MathExpressionsSuite.scala
index e2daaf6b730c5a326ca9a6563289458c2ab52d06..7c9c121b956bbd5bafbaedfd1e11c77d8fae1d87 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/MathExpressionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/MathExpressionsSuite.scala
@@ -236,6 +236,19 @@ class MathExpressionsSuite extends QueryTest {
testOneToOneNonNegativeMathFunction(log1p, math.log1p)
}
+ test("binary log") {
+ val df = Seq[(Integer, Integer)]((123, null)).toDF("a", "b")
+ checkAnswer(
+ df.select(org.apache.spark.sql.functions.log("a"),
+ org.apache.spark.sql.functions.log(2.0, "a"),
+ org.apache.spark.sql.functions.log("b")),
+ Row(math.log(123), math.log(123) / math.log(2), null))
+
+ checkAnswer(
+ df.selectExpr("log(a)", "log(2.0, a)", "log(b)"),
+ Row(math.log(123), math.log(123) / math.log(2), null))
+ }
+
test("abs") {
val input =
Seq[(java.lang.Double, java.lang.Double)]((null, null), (0.0, 0.0), (1.5, 1.5), (-2.5, 2.5))