title: Filter observable array by object property
body: <p>I currently have an array of observables which I'm iterating over using an <code>*ngFor</code> loop with the async pipe.
  I would like to filter the observables by a property value on the object, e.g</p>
  
  <p>Original array:</p>
  
  <pre><code>[{ name: test1,
     type: type1},
   { name: test2,
     type: type2}
   { name: test3,
     type: type1}
   { name: test4,
     type: type2}]
  </code></pre>
  
  <p>I would like to filter this and make two new observable (arrays), one for type1 and one for type2</p>
  
  <p>I tried <code>obs.filter(x =&gt; x.type == "type1)</code> but it returns nothing</p>
  
  <p>I then tried <code>obs.mergeAll().filter(x =&gt; x.type == "type1")</code> and I can subscribe to this and log it to the console correctly but now it doesn't work with my <code>*ngFor</code> (async pipe). I'm guessing it's because the <code>mergeAll</code> means it's no longer an observable array? So do I need to convert it back?</p>