Yes, you're correct. :-) On Thu, 16 Feb 2017 at 14:24 nsengupta <sengupta.nirma...@gmail.com> wrote:
> Thanks, Aljoscha for the clarification. > > I understand that instead of using a flatMap() in the way I am using, I am > better off using : > * a fold (init, fold_func, window_func) first and then > * map to a different type of my choice, inside the window_func, > parameterised above > > I hope I am correct. If so, you don't need to spend time to comment; > ☺otherwise, please give a hint. > > -- Nirmalya > > - > > On Thu, Feb 16, 2017 at 4:12 PM, Aljoscha Krettek [via Apache Flink User > Mailing List archive.] <[hidden email] > <http:///user/SendEmail.jtp?type=node&node=11677&i=0>> wrote: > > Hi, > you would indeed use apply(), or better fold(<initial_value>, > <fold_function>, <window_function>) to map the result of folding your > window to some other data type. If you will, a WindowFunction allows > "mapping" the result of your windowing to a different type. > > Best, > Aljoscha > > On Wed, 15 Feb 2017 at 06:14 nsengupta <[hidden email] > <http:///user/SendEmail.jtp?type=node&node=11665&i=0>> wrote: > > I have gone through this post > < > http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/WindowedStream-operation-questions-td6006.html > > > , where Aljoscha explains that /mapping/ on WindowedStream is /not/ > allowed. > > So, I think I haven't asked the question properly. Here is (hopefully) a > better and easier version: > > 1. I begin with records of type RawMITSIMTuple. > 2. When I group them using a Window, I get an > AllWindowedStream[RawMITSIMTuple]. > 3. I /fold/ the tuples obtained in the Window, which gives me a > DataStream[Vector[RawMITSIMTuple]. > 4. What I need is a DataStream[PositionReport]. So, I need to flatMap > the > output of previous step, where I first get hold of each of the > RawMITSIMTuple and map that to PositionReport. > > val positionReportStream = this > .readRawMITSIMTuplesInjected(envDefault,args(0)) > .assignAscendingTimestamps(e => e.timeOfReport) > .windowAll(TumblingEventTimeWindows.of(Time.seconds(30))) > .fold(Vector[RawMITSIMTuple]())((collectorBin,rawRecord) => { > collectorBin :+ rawRecord) > }) > .flatMap(r => r.map(e => this.preparePositionReport(e))) > > This gives me what I want, but I feel this is verbose and inefficient. Am I > thinking correctly? If so, what is a better idiom to use in such cases? > > -- Nirmalya > > > > > -- > View this message in context: > http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Clarification-use-of-AllWindowedStream-apply-function-tp11627p11630.html > Sent from the Apache Flink User Mailing List archive. mailing list archive > at Nabble.com. > > > > ------------------------------ > If you reply to this email, your message will be added to the discussion > below: > > http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Clarification-use-of-AllWindowedStream-apply-function-tp11627p11665.html > To unsubscribe from Clarification: use of AllWindowedStream.apply() > function, click here. > NAML > <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> > > > > > -- > Software Technologist > http://www.linkedin.com/in/nirmalyasengupta > "If you have built castles in the air, your work need not be lost. That is > where they should be. > Now put the foundation under them." > > ------------------------------ > View this message in context: Re: Clarification: use of > AllWindowedStream.apply() function > <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Clarification-use-of-AllWindowedStream-apply-function-tp11627p11677.html> > Sent from the Apache Flink User Mailing List archive. mailing list archive > <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/> at > Nabble.com. >
