Get the nth element from the inner list of a list of lists in Python
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/13084619/first-items-in-inner-list-efficiently-as-possible">First items in inner list efficiently as possible</a>  </p>
</blockquote>



<p>Lets say I have:</p>

<pre><code>a = [ [1,2], [2,9], [3,7] ]
</code></pre>

<p>I want to retrieve the first element of each of the inner lists:</p>

<pre><code>b = [1,2,3]
</code></pre>

<p>Without having to do this (my current hack):</p>

<pre><code>for inner in a:
    b.append(inner[0])
</code></pre>

<p>I'm sure there's a one liner for it but I don't really know what i'm looking for.</p>
