title: Scala Maps, merging of multiple maps by key
body: <p>I am trying to merge different maps that have the same key (account id), but different values such as average spending, max amount spent and min amount spent. </p>
  
  <pre><code>val a = Map(account1 -&gt; 350.2, account2 -&gt; 547.5, account3 -&gt; 754.4)
  
  val b = Map(account1 -&gt; 1250, account2 -&gt; 3221.785, account3 -&gt; 2900)
  
  val c = Map(account1 -&gt; 50, account2 -&gt; 21.5, account3 -&gt; 12.7)
  </code></pre>
  
  <p>I want:</p>
  
  <pre><code>val d = Map(account1 -&gt; (350.2, 1250 , 50), account2 -&gt; (547.5, 3221.785 , 21.5), ... , ...  )
  </code></pre>
  
  <p>I'd also like to create a list like:</p>
  
  <pre><code>((account1,350.2, 1250 , 50), (account2, 547.5, 3221.785), ... )
  </code></pre>
  
  <p>Any help would be great, thank you very much.</p>