title: How to implement a filter in angular 7
body: <p>I'm trying to implement a filter on my <strong>matTable</strong> with a <strong>DataSource(cdk)</strong>. Now the filter from the Material Example doesn't work since it's not a <strong>MatDataSource</strong> and after a long search, I'm still not sure of a good way to implement it and the different components that would play a part. </p>
  
  <p>I found some examples using pipes (though the official material says it's rather inefficient) and creating a reference for another component of already filtered data. Could someone explain me an efficient way of implementing a filter and the components with their different functions?</p>