title: How do I turn an observable set of two different types to a different third type observable in Typescript with rxjs?
body: <p>So I have a problem of basically I am getting two different services of types Observable and Observable let's say.  They are returned by services and fine on initial load doing something like this (in a constructor of a component in Angular)</p>
  
  <pre><code>combineLatest([this.service.A(), this.service.B()])
    ).subscribe(([A, B]) =&gt; {
      this.C = A.map(x =&gt; {
          return { 
             id: x.id,
             name: x.specificA
          };  //Different type of C 
      }).concat(B.map(x =&gt; {
           return {
              id: x.id,
              name: x.specificB
         };
     });
  </code></pre>
  
  <p>So this works when it is done on constructor and the view loads with my 'C' in this example and the world is right.  However I would like to call an update on the rows at times and go full circle back to my collection and then update.  I was thinking of doing a combineLatest but without a subscribe to get an observable on the component of something like C$: Observable.  Then make that object do all the work in subscriptions and further updates.  Then doing the </p>
  
  <pre><code>  this.C$ = ([this.service.A(), this.service.B()]).pipe(map( //this is wrong))
  </code></pre>
  
  <p>Basically I don't want to subscribe to the observable but set it up from other observables, THEN subscribe to that.  Potentially do a combo with rxjs to take two observable types and make a third type.  Then when the event of an update happens kick off the subscribe of the 'C$' observable.  I know it is probably a simple operation I am just not getting that someone that is good at rxjs could tell me how to combine. </p>