Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1856#discussion_r67050534
--- Diff:
flink-scala/src/main/scala/org/apache/flink/api/scala/DataSet.scala ---
@@ -1599,7 +1601,77 @@ class DataSet[T: ClassTag](set: JavaDataSet[T]) {
def output(outputFormat: OutputFormat[T]): DataSink[T] = {
javaSet.output(outputFormat)
}
-
+
+ /**
+ * Selects an element with minimum value.
+ * <p>
+ * The minimum is computed over the specified fields in lexicographical
order.
+ * <p>
+ * <strong>Example 1</strong>: Given a data set with elements <code>[0,
1], [1, 0]</code>, the
+ * results will be:
+ * <ul>
+ * <li><code>minBy(0)</code>: <code>[0, 1]</code></li>
+ * <li><code>minBy(1)</code>: <code>[1, 0]</code></li>
+ * </ul>
+ * <p>
+ * <strong>Example 2</strong>: Given a data set with elements <code>[0,
0], [0, 1]</code>, the
+ * results will be:
+ * <ul>
+ * <li><code>minBy(0, 1)</code>: <code>[0, 0]</code></li>
+ * </ul>
+ * <p>
+ * If multiple values with minimum value at the specified fields exist,
a random one will be
+ * picked.
+ * <p>
+ * Internally, this operation is implemented as a {@link
ReduceFunction}.
+ *
+ */
+ def minBy(fields: Array[Int]) : ReduceOperator[T] = {
+ if (!getType.isTupleType) {
+ throw new InvalidProgramException("DataSet#minBy(int...) only works
on Tuple types.")
+ }
+
+ return new ReduceOperator[T](
--- End diff --
do not use `return`. In Scala the last expression is implicitly returned.
Do not create a Java API `ReduceOperator`. Use `reduce(new
SelectByMinFunction(...))` instead.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
