How can I divide a RXJS Observable stream into equal N sized arrays?












2














Let's say I have an Observable stream created from an array like so:



const items: Items = [{},{},{},{},{},...];
const obs$ = from(items).pipe(
mergeMap(items => {
return this.getData(items);
})
);


As this code stands, getData() will be called for each item in the array. What I want to do is divide the items array into N equal sized arrays, then have those arrays emitted instead. Then getData() will be called with the individual arrays rather than each item in the original items array.



Basically I need a variation of the toArray() operator but on only portions of the stream that I pre-define.










share|improve this question



























    2














    Let's say I have an Observable stream created from an array like so:



    const items: Items = [{},{},{},{},{},...];
    const obs$ = from(items).pipe(
    mergeMap(items => {
    return this.getData(items);
    })
    );


    As this code stands, getData() will be called for each item in the array. What I want to do is divide the items array into N equal sized arrays, then have those arrays emitted instead. Then getData() will be called with the individual arrays rather than each item in the original items array.



    Basically I need a variation of the toArray() operator but on only portions of the stream that I pre-define.










    share|improve this question

























      2












      2








      2







      Let's say I have an Observable stream created from an array like so:



      const items: Items = [{},{},{},{},{},...];
      const obs$ = from(items).pipe(
      mergeMap(items => {
      return this.getData(items);
      })
      );


      As this code stands, getData() will be called for each item in the array. What I want to do is divide the items array into N equal sized arrays, then have those arrays emitted instead. Then getData() will be called with the individual arrays rather than each item in the original items array.



      Basically I need a variation of the toArray() operator but on only portions of the stream that I pre-define.










      share|improve this question













      Let's say I have an Observable stream created from an array like so:



      const items: Items = [{},{},{},{},{},...];
      const obs$ = from(items).pipe(
      mergeMap(items => {
      return this.getData(items);
      })
      );


      As this code stands, getData() will be called for each item in the array. What I want to do is divide the items array into N equal sized arrays, then have those arrays emitted instead. Then getData() will be called with the individual arrays rather than each item in the original items array.



      Basically I need a variation of the toArray() operator but on only portions of the stream that I pre-define.







      rxjs reactive-programming






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 21 at 5:36









      ijjo

      232619




      232619
























          1 Answer
          1






          active

          oldest

          votes


















          5














          You need buffer operator which has several variations, which are: buffer, bufferCount, bufferTime, bufferToggle, bufferWhen. Buffer Official Documentation



          For example in your case dividing array in 3 size arrays would be:



          const items: Items = [{},{},{},{},{},...];
          const obs$ = from(items).pipe(
          bufferCount(3),
          mergeMap(items => {
          return this.getData(items);
          })
          );





          share|improve this answer





















          • How did I miss that - thanks!
            – ijjo
            Nov 21 at 6:46











          Your Answer






          StackExchange.ifUsing("editor", function () {
          StackExchange.using("externalEditor", function () {
          StackExchange.using("snippets", function () {
          StackExchange.snippets.init();
          });
          });
          }, "code-snippets");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "1"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53405825%2fhow-can-i-divide-a-rxjs-observable-stream-into-equal-n-sized-arrays%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          5














          You need buffer operator which has several variations, which are: buffer, bufferCount, bufferTime, bufferToggle, bufferWhen. Buffer Official Documentation



          For example in your case dividing array in 3 size arrays would be:



          const items: Items = [{},{},{},{},{},...];
          const obs$ = from(items).pipe(
          bufferCount(3),
          mergeMap(items => {
          return this.getData(items);
          })
          );





          share|improve this answer





















          • How did I miss that - thanks!
            – ijjo
            Nov 21 at 6:46
















          5














          You need buffer operator which has several variations, which are: buffer, bufferCount, bufferTime, bufferToggle, bufferWhen. Buffer Official Documentation



          For example in your case dividing array in 3 size arrays would be:



          const items: Items = [{},{},{},{},{},...];
          const obs$ = from(items).pipe(
          bufferCount(3),
          mergeMap(items => {
          return this.getData(items);
          })
          );





          share|improve this answer





















          • How did I miss that - thanks!
            – ijjo
            Nov 21 at 6:46














          5












          5








          5






          You need buffer operator which has several variations, which are: buffer, bufferCount, bufferTime, bufferToggle, bufferWhen. Buffer Official Documentation



          For example in your case dividing array in 3 size arrays would be:



          const items: Items = [{},{},{},{},{},...];
          const obs$ = from(items).pipe(
          bufferCount(3),
          mergeMap(items => {
          return this.getData(items);
          })
          );





          share|improve this answer












          You need buffer operator which has several variations, which are: buffer, bufferCount, bufferTime, bufferToggle, bufferWhen. Buffer Official Documentation



          For example in your case dividing array in 3 size arrays would be:



          const items: Items = [{},{},{},{},{},...];
          const obs$ = from(items).pipe(
          bufferCount(3),
          mergeMap(items => {
          return this.getData(items);
          })
          );






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 21 at 6:18









          Goga Koreli

          345112




          345112












          • How did I miss that - thanks!
            – ijjo
            Nov 21 at 6:46


















          • How did I miss that - thanks!
            – ijjo
            Nov 21 at 6:46
















          How did I miss that - thanks!
          – ijjo
          Nov 21 at 6:46




          How did I miss that - thanks!
          – ijjo
          Nov 21 at 6:46


















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Stack Overflow!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.





          Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


          Please pay close attention to the following guidance:


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53405825%2fhow-can-i-divide-a-rxjs-observable-stream-into-equal-n-sized-arrays%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          Wiesbaden

          Marschland

          Dieringhausen