title: Python Dataframe list unique values based on some criterias
body: <p>I have this simple data set looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/y7cbF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/y7cbF.jpg" alt="enter image description here"></a></p>
  
  <p>After importing it into a dataframe, I want to have a list of unique IDs that contains Type = 2. For instance, the desired output is:</p>
  
  <p>ID
  100654 100655</p>
  
  <p>I think I need to use .groupby but I'm not sure how to make this happen. Can someone please help?</p>
  
  <p>Thanks in advance!</p>