title: Python 2D list slice
body: <p>I looked around and could not find anything this specific, so here goes:</p>
  
  <p>I have a list of lists:</p>
  
  <pre><code>S = [[3,4],[6,7],[10,12]]
  </code></pre>
  
  <p>and I would like to add the 0th index of the ith index element and on to the end of another list:</p>
  
  <pre><code>R = [5,6,7]
  </code></pre>
  
  <p>Normally with a 1D list I could say:</p>
  
  <pre><code>R = R + S[i:]
  </code></pre>
  
  <p>and take all of the elements from the ith index on, but I want the 0th index of the ith index of a 2D S. If we started at i = 1 I would end up with:</p>
  
  <pre><code>R = [5,6,7,6,10]
  </code></pre>
  
  <p>Also, I don't want to use for loops I want a list slice method that will work (if there is one) because it needs to be within a certain bound.</p>