title: Fastest way to get the probabilties for which an element is present in a list
body: <p>I created a function that will return a dictionary with the input list elements and the probability of selecting that item from the list: </p>
  
  <pre><code>from collections import Counter
  
  def proba(x):
      n = len(x)
      return {key: val/n for key, val in dict(Counter(x)).items()}
  </code></pre>
  
  <p>Is there a faster solution to this ? I don't need the output to be in a kay:value pair if the output order of probabilities corresponds to the input order of elements.</p>