title: Re-ordered a nested sorted-map with Clojure
body: <p>I have this sorted map:</p>
  
  <pre><code> (def my-map {1 {:foo "String_1" :ordnen 5 } 
                2 {:foo "String_2" :ordnen 4} 
                3 {:foo "String_3" :ordnen 3} 
                4 {:foo "String_4" :ordnen 1} })
  </code></pre>
  
  <p>And I need to re-ordered it in an ascendant way using the value kept in the <strong>:ordnen</strong> keyword. So, the final sorted-map would be like:  </p>
  
  <pre><code>  {4 {:foo "String_4" :ordnen 1}
     3 {:foo "String_3" :ordnen 3}
     2 {:foo "String_2" :ordnen 4} 
     1 {:foo "String_1" :ordnen 5 }}
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>(into (sorted-map-by (fn [key1 key2] (compare (:ordnen key1) (:ordnen key2)))) my-map)
  </code></pre>
  
  <p>but I don't understand how to get and compare the value of <strong>:ordnen</strong> .</p>