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_r330283164
##########
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 {
Review comment:
nit: style
```
def aggregate(
expr: Column,
zero: Column,
merge: (Column, Column) => Column,
finish: Column => Column): Column = withExpr {
...
}
```
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