title: python filter and list and apply "filtered indices" to another list
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/10274774/python-elegant-and-efficient-ways-to-mask-a-list">Python: Elegant and efficient ways to mask a list</a>  </p>
  </blockquote>
  
  
  
  <p>I have two equal sized lists, something like:</p>
  
  <pre><code>a=["alpha","beta","kappa","gamma","lambda"]
  b=[1,2,None,3,4,5]
  </code></pre>
  
  <p>What I would like to do is identify and delete the none element in list [b] and then remove the corresponding element in list [a]. Here, for example, I would like to delete none and "kappa".</p>
  
  <p>I am aware of:</p>
  
  <p>filter(bool,b)</p>
  
  <p>which would remove the None elements from [b], but, how do I go about deleting the corresponding entry in list[a]?</p>
  
  <p>I tried zip, something like (the idea was to pack and unpack):</p>
  
  <pre><code>a=["a","b","c","d","e"]
  b=[1,2,None,3,4]
  c=zip(a,b)
  d=filter(bool,c)
  </code></pre>
  
  <p>..but this does not work. [d] still has the none elements.</p>
  
  <p>I would appreciate any pythonic way to achieve this.</p>