[SPARK-7188] added python support for math DataFrame functions

python/pyspark/sql/functions.py

@@ -54,7 +54,7 @@ def _(col):
     'upper': 'Converts a string expression to upper case.',
     'lower': 'Converts a string expression to upper case.',
     'sqrt': 'Computes the square root of the specified float value.',
-    'abs': 'Computes the absolutle value.',
+    'abs': 'Computes the absolute value.',
 
     'max': 'Aggregate function: returns the maximum value of the expression in a group.',
     'min': 'Aggregate function: returns the minimum value of the expression in a group.',

python/pyspark/sql/mathfunctions.py

@@ -0,0 +1,101 @@
+#
+# 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,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+A collection of builtin math functions
+"""
+
+from pyspark import SparkContext
+from pyspark.sql.dataframe import Column
+
+__all__ = []
+
+
+def _create_unary_mathfunction(name, doc=""):
+    """ Create a unary mathfunction by name"""
+    def _(col):
+        sc = SparkContext._active_spark_context
+        jc = getattr(sc._jvm.mathfunctions, name)(col._jc if isinstance(col, Column) else col)
+        return Column(jc)
+    _.__name__ = name
+    _.__doc__ = doc
+    return _
+
+
+def _create_binary_mathfunction(name, doc=""):
+    """ Create a binary mathfunction by name"""
+    def _(col1, col2):
+        sc = SparkContext._active_spark_context
+        # users might write ints for simplicity. This would throw an error on the JVM side.
+        if type(col1) is int:
+            col1 = col1 * 1.0
+        if type(col2) is int:
+            col2 = col2 * 1.0
+        jc = getattr(sc._jvm.mathfunctions, name)(col1._jc if isinstance(col1, Column) else col1,
+                                                  col2._jc if isinstance(col2, Column) else col2)
+        return Column(jc)
+    _.__name__ = name
+    _.__doc__ = doc
+    return _
+
+
+# math functions are found under another object therefore, they need to be handled separately
+_mathfunctions = {
+    'acos': 'Computes the cosine inverse of the given value; the returned angle is in the range' +
+            '0.0 through pi.',
+    'asin': 'Computes the sine inverse of the given value; the returned angle is in the range' +
+            '-pi/2 through pi/2.',
+    'atan': 'Computes the tangent inverse of the given value.',
+    'cbrt': 'Computes the cube-root of the given value.',
+    'ceil': 'Computes the ceiling of the given value.',
+    'cos': 'Computes the cosine of the given value.',
+    'cosh': 'Computes the hyperbolic cosine of the given value.',
+    'exp': 'Computes the exponential of the given value.',
+    'expm1': 'Computes the exponential of the given value minus one.',
+    'floor': 'Computes the floor of the given value.',
+    'log': 'Computes the natural logarithm of the given value.',
+    'log10': 'Computes the logarithm of the given value in Base 10.',
+    'log1p': 'Computes the natural logarithm of the given value plus one.',
+    'rint': 'Returns the double value that is closest in value to the argument and' +
+            ' is equal to a mathematical integer.',
+    'signum': 'Computes the signum of the given value.',
+    'sin': 'Computes the sine of the given value.',
+    'sinh': 'Computes the hyperbolic sine of the given value.',
+    'tan': 'Computes the tangent of the given value.',
+    'tanh': 'Computes the hyperbolic tangent of the given value.',
+    'toDeg': 'Converts an angle measured in radians to an approximately equivalent angle ' +
+             'measured in degrees.',
+    'toRad': 'Converts an angle measured in degrees to an approximately equivalent angle ' +
+             'measured in radians.'
+}
+
+# math functions that take two arguments as input
+_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.'
+}
+
+for _name, _doc in _mathfunctions.items():
+    globals()[_name] = _create_unary_mathfunction(_name, _doc)
+for _name, _doc in _binary_mathfunctions.items():
+    globals()[_name] = _create_binary_mathfunction(_name, _doc)
+del _name, _doc
+__all__ += _mathfunctions.keys()
+__all__ += _binary_mathfunctions.keys()
+__all__.sort()

python/pyspark/sql/tests.py

@@ -387,6 +387,35 @@ def test_aggregator(self):
         self.assertTrue(95 < g.agg(functions.approxCountDistinct(df.key)).first()[0])
         self.assertEqual(100, g.agg(functions.countDistinct(df.value)).first()[0])
 
+    def test_math_functions(self):
+        df = self.sc.parallelize([Row(a=i, b=2 * i) for i in range(10)]).toDF()
+        from pyspark.sql import mathfunctions as functions
+        import math
+
+        def get_values(l):
+            return [j[0] for j in l]
+
+        def assert_close(a, b):
+            c = get_values(b)
+            diff = [abs(v - c[k]) < 1e-6 for k, v in enumerate(a)]
+            return sum(diff) == len(a)
+        assert_close([math.cos(i) for i in range(10)],
+                     df.select(functions.cos(df.a)).collect())
+        assert_close([math.cos(i) for i in range(10)],
+                     df.select(functions.cos("a")).collect())
+        assert_close([math.sin(i) for i in range(10)],
+                     df.select(functions.sin(df.a)).collect())
+        assert_close([math.sin(i) for i in range(10)],
+                     df.select(functions.sin(df['a'])).collect())
+        assert_close([math.pow(i, 2 * i) for i in range(10)],
+                     df.select(functions.pow(df.a, df.b)).collect())
+        assert_close([math.pow(i, 2) for i in range(10)],
+                     df.select(functions.pow(df.a, 2)).collect())
+        assert_close([math.pow(i, 2) for i in range(10)],
+                     df.select(functions.pow(df.a, 2.0)).collect())
+        assert_close([math.hypot(i, 2 * i) for i in range(10)],
+                     df.select(functions.hypot(df.a, df.b)).collect())
+
     def test_save_and_load(self):
         df = self.df
         tmpPath = tempfile.mkdtemp()

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathfuncs/binary.scala

@@ -65,12 +65,6 @@ abstract class BinaryMathExpression(f: (Double, Double) => Double, name: String)
   }
 }
 
-case class Pow(left: Expression, right: Expression) extends BinaryMathExpression(math.pow, "POWER")
-
-case class Hypot(
-    left: Expression,
-    right: Expression) extends BinaryMathExpression(math.hypot, "HYPOT")
-
 case class Atan2(
     left: Expression,
     right: Expression) extends BinaryMathExpression(math.atan2, "ATAN2") {
@@ -91,3 +85,9 @@ case class Atan2(
     }
   }
 }
+
+case class Hypot(
+    left: Expression,
+    right: Expression) extends BinaryMathExpression(math.hypot, "HYPOT")
+
+case class Pow(left: Expression, right: Expression) extends BinaryMathExpression(math.pow, "POWER")

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathfuncs/unary.scala

@@ -25,27 +25,16 @@ import org.apache.spark.sql.types._
  * input format, therefore these functions extend `ExpectsInputTypes`.
  * @param name The short name of the function
  */
-abstract class MathematicalExpression(name: String)
+abstract class MathematicalExpression(f: Double => Double, name: String)
   extends UnaryExpression with Serializable with ExpectsInputTypes {
   self: Product =>
   type EvaluatedType = Any
 
+  override def expectedChildTypes: Seq[DataType] = Seq(DoubleType)
   override def dataType: DataType = DoubleType
   override def foldable: Boolean = child.foldable
   override def nullable: Boolean = true
   override def toString: String = s"$name($child)"
-}
-
-/**
- * A unary expression specifically for math functions that take a `Double` as input and return
- * a `Double`.
- * @param f The math function.
- * @param name The short name of the function
- */
-abstract class MathematicalExpressionForDouble(f: Double => Double, name: String)
-  extends MathematicalExpression(name) { self: Product =>
-
-  override def expectedChildTypes: Seq[DataType] = Seq(DoubleType)
 
   override def eval(input: Row): Any = {
     val evalE = child.eval(input)
@@ -58,111 +47,46 @@ abstract class MathematicalExpressionForDouble(f: Double => Double, name: String
   }
 }
 
-/**
- * A unary expression specifically for math functions that take an `Int` as input and return
- * an `Int`.
- * @param f The math function.
- * @param name The short name of the function
- */
-abstract class MathematicalExpressionForInt(f: Int => Int, name: String)
-  extends MathematicalExpression(name) { self: Product =>
+case class Acos(child: Expression) extends MathematicalExpression(math.acos, "ACOS")
 
-  override def dataType: DataType = IntegerType
-  override def expectedChildTypes: Seq[DataType] = Seq(IntegerType)
+case class Asin(child: Expression) extends MathematicalExpression(math.asin, "ASIN")
 
-  override def eval(input: Row): Any = {
-    val evalE = child.eval(input)
-    if (evalE == null) null else f(evalE.asInstanceOf[Int])
-  }
-}
+case class Atan(child: Expression) extends MathematicalExpression(math.atan, "ATAN")
 
-/**
- * A unary expression specifically for math functions that take a `Float` as input and return
- * a `Float`.
- * @param f The math function.
- * @param name The short name of the function
- */
-abstract class MathematicalExpressionForFloat(f: Float => Float, name: String)
-  extends MathematicalExpression(name) { self: Product =>
+case class Cbrt(child: Expression) extends MathematicalExpression(math.cbrt, "CBRT")
 
-  override def dataType: DataType = FloatType
-  override def expectedChildTypes: Seq[DataType] = Seq(FloatType)
+case class Ceil(child: Expression) extends MathematicalExpression(math.ceil, "CEIL")
 
-  override def eval(input: Row): Any = {
-    val evalE = child.eval(input)
-    if (evalE == null) {
-      null
-    } else {
-      val result = f(evalE.asInstanceOf[Float])
-      if (result.isNaN) null else result
-    }
-  }
-}
-
-/**
- * A unary expression specifically for math functions that take a `Long` as input and return
- * a `Long`.
- * @param f The math function.
- * @param name The short name of the function
- */
-abstract class MathematicalExpressionForLong(f: Long => Long, name: String)
-  extends MathematicalExpression(name) { self: Product =>
-
-  override def dataType: DataType = LongType
-  override def expectedChildTypes: Seq[DataType] = Seq(LongType)
-
-  override def eval(input: Row): Any = {
-    val evalE = child.eval(input)
-    if (evalE == null) null else f(evalE.asInstanceOf[Long])
-  }
-}
-
-case class Sin(child: Expression) extends MathematicalExpressionForDouble(math.sin, "SIN")
-
-case class Asin(child: Expression) extends MathematicalExpressionForDouble(math.asin, "ASIN")
-
-case class Sinh(child: Expression) extends MathematicalExpressionForDouble(math.sinh, "SINH")
-
-case class Cos(child: Expression) extends MathematicalExpressionForDouble(math.cos, "COS")
+case class Cos(child: Expression) extends MathematicalExpression(math.cos, "COS")
 
-case class Acos(child: Expression) extends MathematicalExpressionForDouble(math.acos, "ACOS")
+case class Cosh(child: Expression) extends MathematicalExpression(math.cosh, "COSH")
 
-case class Cosh(child: Expression) extends MathematicalExpressionForDouble(math.cosh, "COSH")
+case class Exp(child: Expression) extends MathematicalExpression(math.exp, "EXP")
 
-case class Tan(child: Expression) extends MathematicalExpressionForDouble(math.tan, "TAN")
+case class Expm1(child: Expression) extends MathematicalExpression(math.expm1, "EXPM1")
 
-case class Atan(child: Expression) extends MathematicalExpressionForDouble(math.atan, "ATAN")
+case class Floor(child: Expression) extends MathematicalExpression(math.floor, "FLOOR")
 
-case class Tanh(child: Expression) extends MathematicalExpressionForDouble(math.tanh, "TANH")
+case class Log(child: Expression) extends MathematicalExpression(math.log, "LOG")
 
-case class Ceil(child: Expression) extends MathematicalExpressionForDouble(math.ceil, "CEIL")
+case class Log10(child: Expression) extends MathematicalExpression(math.log10, "LOG10")
 
-case class Floor(child: Expression) extends MathematicalExpressionForDouble(math.floor, "FLOOR")
+case class Log1p(child: Expression) extends MathematicalExpression(math.log1p, "LOG1P")
 
-case class Rint(child: Expression) extends MathematicalExpressionForDouble(math.rint, "ROUND")
+case class Rint(child: Expression) extends MathematicalExpression(math.rint, "ROUND")
 
-case class Cbrt(child: Expression) extends MathematicalExpressionForDouble(math.cbrt, "CBRT")
+case class Signum(child: Expression) extends MathematicalExpression(math.signum, "SIGNUM")
 
-case class Signum(child: Expression) extends MathematicalExpressionForDouble(math.signum, "SIGNUM")
+case class Sin(child: Expression) extends MathematicalExpression(math.sin, "SIN")
 
-case class ISignum(child: Expression) extends MathematicalExpressionForInt(math.signum, "ISIGNUM")
+case class Sinh(child: Expression) extends MathematicalExpression(math.sinh, "SINH")
 
-case class FSignum(child: Expression) extends MathematicalExpressionForFloat(math.signum, "FSIGNUM")
+case class Tan(child: Expression) extends MathematicalExpression(math.tan, "TAN")
 
-case class LSignum(child: Expression) extends MathematicalExpressionForLong(math.signum, "LSIGNUM")
+case class Tanh(child: Expression) extends MathematicalExpression(math.tanh, "TANH")
 
 case class ToDegrees(child: Expression) 
-  extends MathematicalExpressionForDouble(math.toDegrees, "DEGREES")
+  extends MathematicalExpression(math.toDegrees, "DEGREES")
 
 case class ToRadians(child: Expression) 
-  extends MathematicalExpressionForDouble(math.toRadians, "RADIANS")
-
-case class Log(child: Expression) extends MathematicalExpressionForDouble(math.log, "LOG")
-
-case class Log10(child: Expression) extends MathematicalExpressionForDouble(math.log10, "LOG10")
-
-case class Log1p(child: Expression) extends MathematicalExpressionForDouble(math.log1p, "LOG1P")
-
-case class Exp(child: Expression) extends MathematicalExpressionForDouble(math.exp, "EXP")
-
-case class Expm1(child: Expression) extends MathematicalExpressionForDouble(math.expm1, "EXPM1")
+  extends MathematicalExpression(math.toRadians, "RADIANS")

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala

@@ -1253,18 +1253,6 @@ class ExpressionEvaluationSuite extends ExpressionEvaluationBaseSuite {
     unaryMathFunctionEvaluation[Double](Signum, math.signum)
   }
 
-  test("isignum") {
-    unaryMathFunctionEvaluation[Int](ISignum, math.signum, (-5 to 5))
-  }
-
-  test("fsignum") {
-    unaryMathFunctionEvaluation[Float](FSignum, math.signum, (-5 to 5).map(_.toFloat))
-  }
-
-  test("lsignum") {
-    unaryMathFunctionEvaluation[Long](LSignum, math.signum, (5 to 5).map(_.toLong))
-  }
-
   test("log") {
     unaryMathFunctionEvaluation(Log, math.log, (0 to 20).map(_ * 0.1))
     unaryMathFunctionEvaluation(Log, math.log, (-5 to -1).map(_ * 0.1), true)