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https://issues.apache.org/jira/browse/FLINK-3650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15331619#comment-15331619
]
ASF GitHub Bot commented on FLINK-3650:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1856#discussion_r67150746
--- Diff:
flink-scala/src/main/scala/org/apache/flink/api/scala/DataSet.scala ---
@@ -699,6 +700,55 @@ class DataSet[T: ClassTag](set: JavaDataSet[T]) {
}
/**
+ * Selects an element with minimum value.
+ *
+ * The minimum is computed over the specified fields in lexicographical
order.
+ *
+ * Example 1: Given a data set with elements [0, 1], [1, 0], the
+ * results will be:
+ *
+ * minBy(0)[0, 1]
+ * minBy(1)[1, 0]
+ * Example 2: Given a data set with elements [0, 0], [0, 1], the
+ * results will be:
+ * minBy(0, 1)[0, 0]
+ * If multiple values with minimum value at the specified fields exist,
a random one will be
+ * picked.
+ * Internally, this operation is implemented as a {@link
ReduceFunction}.
+ */
+ def minBy(fields: Int*) : DataSet[T] = {
+ if (!getType.isTupleType) {
+ throw new InvalidProgramException("DataSet#minBy(int...) only works
on Tuple types.")
+ }
+
+ reduce(new
SelectByMinFunction[T](getType.asInstanceOf[TupleTypeInfoBase[T]],
fields.toArray))
+ }
+
+ /**
+ * Selects an element with maximum value.
+ *
+ * The maximum is computed over the specified fields in lexicographical
order.
+ *
+ * Example 1: Given a data set with elements [0, 1], [1, 0], the
+ * results will be:
+ *
+ * maxBy(0)[1, 0]
+ * maxBy(1)[0, 1]
+ * Example 2: Given a data set with elements [0, 0], [0, 1], the
+ * results will be:
+ * maxBy(0, 1)[0, 1]
+ * If multiple values with maximum value at the specified fields exist,
a random one will be
+ * picked
+ * Internally, this operation is implemented as a {@link
ReduceFunction}.
+ *
+ */
+ def maxBy(fields: Int*) : DataSet[T] = {
+ if (!getType.isTupleType) {
+ throw new InvalidProgramException("DataSet#maxBy(int...) only works
on Tuple types.")
+ }
+ reduce(new
SelectByMaxFunction[T](getType.asInstanceOf[TupleTypeInfoBase[T]],
fields.toArray))
+ }
--- End diff --
Add a new line
> Add maxBy/minBy to Scala DataSet API
> ------------------------------------
>
> Key: FLINK-3650
> URL: https://issues.apache.org/jira/browse/FLINK-3650
> Project: Flink
> Issue Type: Improvement
> Components: Java API, Scala API
> Affects Versions: 1.1.0
> Reporter: Till Rohrmann
> Assignee: ramkrishna.s.vasudevan
>
> The stable Java DataSet API contains the API calls {{maxBy}} and {{minBy}}.
> These methods are not supported by the Scala DataSet API. These methods
> should be added in order to have a consistent API.
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