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https://issues.apache.org/jira/browse/BEAM-7700?focusedWorklogId=282476&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-282476
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ASF GitHub Bot logged work on BEAM-7700:
----------------------------------------
Author: ASF GitHub Bot
Created on: 25/Jul/19 06:51
Start Date: 25/Jul/19 06:51
Worklog Time Spent: 10m
Work Description: robinyqiu commented on pull request #9129: [BEAM-7700]
Java transform catalog
URL: https://github.com/apache/beam/pull/9129#discussion_r307122989
##########
File path: website/src/documentation/transforms/java/element-wise/partition.md
##########
@@ -0,0 +1,62 @@
+---
+layout: section
+title: "Partition"
+permalink: /documentation/transforms/java/elementwise/partition/
+section_menu: section-menu/documentation.html
+---
+<!--
+Licensed 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.
+-->
+# Partition
+<table align="left">
+ <a target="_blank" class="button"
+
href="https://beam.apache.org/releases/javadoc/current/index.html?org/apache/beam/sdk/transforms/Partition.html";>
+ <img src="https://beam.apache.org/images/logos/sdks/java.png";
width="20px" height="20px"
+ alt="Javadoc" />
+ Javadoc
+ </a>
+</table>
+<br>
+Separates elements in a collection into multiple output collections. The
partitioning function contains the logic that determines how to separate the
elements of the input collection into each resulting partition output
collection.
+
+The number of partitions must be determined at graph construction time. You
cannot determine the number of partitions in mid-pipeline.
+
+See more information in the [Beam Programming Guide]({{ site.baseurl
}}/documentation/programming-guide/#partition).
+
+## Examples
+**Example**: dividing a `PCollection` into percentile groups
+
+```java
+// Provide an int value with the desired number of result partitions, and a
PartitionFn that represents the
+// partitioning function. In this example, we define the PartitionFn in-line.
Returns a PCollectionList
+// containing each of the resulting partitions as individual PCollection
objects.
+PCollection<Student> students = ...;
+// Split students up into 10 partitions, by percentile:
+PCollectionList<Student> studentsByPercentile =
+ students.apply(Partition.of(10, new PartitionFn<Student>() {
+ public int partitionFor(Student student, int numPartitions) {
+ return student.getPercentile() // 0..99
+ * numPartitions / 100;
+ }}));
+
+// You can extract each partition from the PCollectionList using the get
method, as follows:
+PCollection<Student> fortiethPercentile = studentsByPercentile.get(4);
+```
+
+## Related transforms
+* [Filter]({{ site.baseurl
}}/documentation/transforms/java/elementwise/filter) is useful if the function
is just
+ deciding whether to output an element or not.
+* [ParDo]({{ site.baseurl }}/documentation/transforms/java/elementwise/pardo)
is the most general element-wise mapping
+ operation, and includes other abilities such as multiple output collections
and side-inputs.
+* [CoGroupByKey]({{ site.baseurl
}}/documentation/transforms/java/aggregation/cogroupbykey)
Review comment:
Not sure how `CoGroupByKey` is related.
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Issue Time Tracking
-------------------
Worklog Id: (was: 282476)
Time Spent: 1h 50m (was: 1h 40m)
> Java transform catalog
> ----------------------
>
> Key: BEAM-7700
> URL: https://issues.apache.org/jira/browse/BEAM-7700
> Project: Beam
> Issue Type: Improvement
> Components: website
> Reporter: Rose Nguyen
> Assignee: Rose Nguyen
> Priority: Minor
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> Create catalog of core transforms (Java)
> -Java transforms overview
> -Links to Javadocs
> -Brief description
> -Related transforms
> -Links to programming guide
> -Examples section to integrate Colab notebooks
>
> See BEAM-7464 for Python.
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