title: How can I divide a RXJS Observable stream into equal N sized arrays?
body: <p>Let's say I have an Observable stream created from an array like so:</p>
  
  <pre><code>const items: Items = [{},{},{},{},{},...];
  const obs$ = from(items).pipe(
      mergeMap(items =&gt; {
          return this.getData(items);
      })
  );
  </code></pre>
  
  <p>As this code stands, <code>getData()</code> 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 <code>getData()</code> will be called with the individual arrays rather than each item in the original items array.</p>
  
  <p>Basically I need a variation of the <code>toArray()</code> operator but on only portions of the stream that I pre-define.</p>