title: Merge several dictionaries creating array on different values
body: <p>So I have a list with several dictionaries, they all have the same keys. Some dictionaries are the same but one value is different. How could I merge them into 1 dictionary having that different values as array?</p>
  
  <p>Let me give you an example:</p>
  
  <p>let's say I have this dictionaries</p>
  
  <pre><code>[{'a':1, 'b':2,'c':3},{'a':1, 'b':2,'c':4},{'a':1, 'b':3,'c':3},{'a':1, 'b':3,'c':4}]
  </code></pre>
  
  <p>My desired output would be this:</p>
  
  <pre><code>[{'a':1, 'b':2,'c':[3,4]},{'a':1, 'b':3,'c':[3,4]}]
  </code></pre>
  
  <p>I've tried using <code>for</code> and <code>if</code> nested, but it's too expensive and nasty, and I'm sure there must be a better way. Could you give me a hand?</p>
  
  <p>How could I do that for any kind of dictionary assuming that the amount of keys is the same on the dictionaries and knowing the name of the key to be merged as array (<code>c</code> in this case)</p>
  
  <p>thanks!</p>