You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@flink.apache.org by se...@apache.org on 2015/11/19 20:34:48 UTC
flink git commit: [hotfix] [docs] Fix errors in streaming docs for
fold()
Repository: flink
Updated Branches:
refs/heads/master 38cf0c610 -> 2f013a204
[hotfix] [docs] Fix errors in streaming docs for fold()
Project: http://git-wip-us.apache.org/repos/asf/flink/repo
Commit: http://git-wip-us.apache.org/repos/asf/flink/commit/2f013a20
Tree: http://git-wip-us.apache.org/repos/asf/flink/tree/2f013a20
Diff: http://git-wip-us.apache.org/repos/asf/flink/diff/2f013a20
Branch: refs/heads/master
Commit: 2f013a20414a825bb6fc31dfc96ff562141e209b
Parents: 38cf0c6
Author: Stephan Ewen <se...@apache.org>
Authored: Thu Nov 19 20:33:17 2015 +0100
Committer: Stephan Ewen <se...@apache.org>
Committed: Thu Nov 19 20:33:17 2015 +0100
----------------------------------------------------------------------
docs/apis/streaming_guide.md | 48 +++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 20 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/flink/blob/2f013a20/docs/apis/streaming_guide.md
----------------------------------------------------------------------
diff --git a/docs/apis/streaming_guide.md b/docs/apis/streaming_guide.md
index fb6d86a..db1f3a7 100644
--- a/docs/apis/streaming_guide.md
+++ b/docs/apis/streaming_guide.md
@@ -519,22 +519,23 @@ keyedStream.reduce(new ReduceFunction<Integer>() {
</td>
</tr>
<tr>
- <td><strong>Fold</strong><br>DataStream → DataStream</td>
+ <td><strong>Fold</strong><br>KeyedStream → DataStream</td>
<td>
<p>A "rolling" fold on a keyed data stream with an initial value.
Combines the current element with the last folded value and
emits the new value.
<br/>
<br/>
- A fold function that creates a stream of partial sums:</p>
+ <p>A fold function that, when applied on the sequence (1,2,3,4,5),
+ emits the sequence "start-1", "start-1-2", "start-1-2-3", ...</p>
{% highlight java %}
-keyedStream.fold(0, new ReduceFunction<Integer>() {
- @Override
- public Integer fold(Integer accumulator, Integer value)
- throws Exception {
- return accumulator + value;
- }
-});
+DataStream<String> result =
+ keyedStream.fold("start", new FoldFunction<Integer, String>() {
+ @Override
+ public String fold(String current, Integer value) {
+ return current + "-" + value;
+ }
+ });
{% endhighlight %}
</p>
</td>
@@ -621,11 +622,13 @@ windowedStream.reduce (new ReduceFunction<Tuple2<String,Integer>() {
<tr>
<td><strong>Window Fold</strong><br>WindowedStream → DataStream</td>
<td>
- <p>Applies a functional fold function to the window and returns the folded value.</p>
+ <p>Applies a functional fold function to the window and returns the folded value.
+ The example function, when applied on the sequence (1,2,3,4,5),
+ folds the sequence into the string "start-1-2-3-4-5":</p>
{% highlight java %}
-windowedStream.fold (new Tuple2<String,Integer>("Sum of all", 0), new FoldFunction<Tuple2<String,Integer>() {
- public Tuple2<String, Integer> fold(Tuple2<String, Integer> acc, Tuple2<String, Integer> value) throws Exception {
- return new Tuple2<String,Integer>(acc.f0, acc.f1 + value.f1);
+windowedStream.fold("start-", new FoldFunction<Integer, String>() {
+ public String fold(String current, Integer value) {
+ return current + "-" + value;
}
};
{% endhighlight %}
@@ -884,16 +887,18 @@ keyedStream.reduce { _ + _ }
</td>
</tr>
<tr>
- <td><strong>Fold</strong><br>DataStream → DataStream</td>
+ <td><strong>Fold</strong><br>KeyedStream → DataStream</td>
<td>
<p>A "rolling" fold on a keyed data stream with an initial value.
Combines the current element with the last folded value and
emits the new value.
<br/>
<br/>
- A fold function that creates a stream of partial sums:</p>
+ <p>A fold function that, when applied on the sequence (1,2,3,4,5),
+ emits the sequence "start-1", "start-1-2", "start-1-2-3", ...</p>
{% highlight scala %}
-keyedStream.fold { 0, _ + _ }
+val result: DataStream[String] =
+ keyedStream.fold("start", (str, i) => { str + "-" + i })
{% endhighlight %}
</p>
</td>
@@ -965,10 +970,13 @@ windowedStream.reduce { _ + _ }
<tr>
<td><strong>Window Fold</strong><br>WindowedStream → DataStream</td>
<td>
- <p>Applies a functional fold function to the window and returns the folded value.</p>
- {% highlight java %}
-windowedStream.fold { 0, _ + _ }
- {% endhighlight %}
+ <p>Applies a functional fold function to the window and returns the folded value.
+ The example function, when applied on the sequence (1,2,3,4,5),
+ folds the sequence into the string "start-1-2-3-4-5":</p>
+ {% highlight scala %}
+val result: DataStream[String] =
+ windowedStream.fold("start", (str, i) => { str + "-" + i })
+ {% endhighlight %}
</td>
</tr>
<tr>