ueshin commented on a change in pull request #24232: [SPARK-27297] [SQL] Add
higher order functions to scala API
URL: https://github.com/apache/spark/pull/24232#discussion_r330283268
##########
File path: sql/core/src/main/scala/org/apache/spark/sql/functions.scala
##########
@@ -3385,6 +3385,162 @@ object functions {
ArrayExcept(col1.expr, col2.expr)
}
+ private def createLambda(f: Column => Column) = {
+ val x = UnresolvedNamedLambdaVariable(Seq("x"))
+ val function = f(Column(x)).expr
+ LambdaFunction(function, Seq(x))
+ }
+
+ private def createLambda(f: (Column, Column) => Column) = {
+ val x = UnresolvedNamedLambdaVariable(Seq("x"))
+ val y = UnresolvedNamedLambdaVariable(Seq("y"))
+ val function = f(Column(x), Column(y)).expr
+ LambdaFunction(function, Seq(x, y))
+ }
+
+ private def createLambda(f: (Column, Column, Column) => Column) = {
+ val x = UnresolvedNamedLambdaVariable(Seq("x"))
+ val y = UnresolvedNamedLambdaVariable(Seq("y"))
+ val z = UnresolvedNamedLambdaVariable(Seq("z"))
+ val function = f(Column(x), Column(y), Column(z)).expr
+ LambdaFunction(function, Seq(x, y, z))
+ }
+
+ /**
+ * Returns an array of elements after applying a tranformation to each
element
+ * in the input array.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def transform(column: Column, f: Column => Column): Column = withExpr {
+ ArrayTransform(column.expr, createLambda(f))
+ }
+
+ /**
+ * Returns an array of elements after applying a tranformation to each
element
+ * in the input array.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def transform(column: Column, f: (Column, Column) => Column): Column =
withExpr {
+ ArrayTransform(column.expr, createLambda(f))
+ }
+
+ /**
+ * Returns whether a predicate holds for one or more elements in the array.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def exists(column: Column, f: Column => Column): Column = withExpr {
+ ArrayExists(column.expr, createLambda(f))
+ }
+
+ /**
+ * Returns whether a predicate holds for every element in the array.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def forall(column: Column, f: Column => Column): Column = withExpr {
+ ArrayForAll(column.expr, createLambda(f))
+ }
+
+ /**
+ * Returns an array of elements for which a predicate holds in a given array.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def filter(column: Column, f: Column => Column): Column = withExpr {
+ ArrayFilter(column.expr, createLambda(f))
+ }
+
+ /**
+ * Applies a binary operator to an initial state and all elements in the
array,
+ * and reduces this to a single state. The final state is converted into the
final result
+ * by applying a finish function.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def aggregate(expr: Column, zero: Column, merge: (Column, Column) => Column,
+ finish: Column => Column): Column = withExpr {
+ ArrayAggregate(
+ expr.expr,
+ zero.expr,
+ createLambda(merge),
+ createLambda(finish)
+ )
+ }
+
+ /**
+ * Applies a binary operator to an initial state and all elements in the
array,
+ * and reduces this to a single state.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def aggregate(expr: Column, zero: Column, merge: (Column, Column) =>
Column): Column =
+ aggregate(expr, zero, merge, c => c)
+
+ /**
+ * Merge two given arrays, element-wise, into a signle array using a
function.
+ * If one array is shorter, nulls are appended at the end to match the
length of the longer
+ * array, before applying the function.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def zip_with(left: Column, right: Column, f: (Column, Column) => Column):
Column = withExpr {
+ ZipWith(left.expr, right.expr, createLambda(f))
+ }
+
+ /**
+ * Applies a function to every key-value pair in a map and returns
+ * a map with the results of those applications as the new keys for the
pairs.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def transform_keys(expr: Column, f: (Column, Column) => Column): Column =
withExpr {
+ TransformKeys(expr.expr, createLambda(f))
+ }
+
+ /**
+ * Applies a function to every key-value pair in a map and returns
+ * a map with the results of those applications as the new values for the
pairs.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def transform_values(expr: Column, f: (Column, Column) => Column): Column =
withExpr {
+ TransformValues(expr.expr, createLambda(f))
+ }
+
+ /**
+ * Returns a map whose key-value pairs satisfy a predicate.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def map_filter(expr: Column, f: (Column, Column) => Column): Column =
withExpr {
+ MapFilter(expr.expr, createLambda(f))
+ }
+
+ /**
+ * Merge two given maps, key-wise into a single map using a function.
+ *
+ * @group collection_funcs
+ * @since 3.0.0
+ */
+ def map_zip_with(left: Column, right: Column,
+ f: (Column, Column, Column) => Column): Column = withExpr {
Review comment:
ditto.
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