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>
