title: I would like to extract the columns of each element of a list in R
body: <p>I'd to extract the 3rd column (c) of each element in this list and store the result.
  (I've listed the data frame in this example so that it looks like the long list of lists I have):</p>
  <pre><code>set.seed(59)
  df&lt;- data.frame(a=c(1,4,5,2),b=c(9,2,7,4),c=c(5,2,9,4))
  df1&lt;- data.frame(df,2*df)
  df1&lt;- list(df,2*df)
  
  [[1]]
    a b c
  1 1 9 5
  2 4 2 2
  3 5 7 9
  4 2 4 4
  
  [[2]]
     a  b  c
  1  2 18 10
  2  8  4  4
  3 10 14 18
  4  4  8  8
  </code></pre>
  <p>Seems fairly simple for just one element</p>
  <pre><code>&gt; df1[[1]][&quot;c&quot;]
   c
  1 5
  2 2
  3 9
  4 4
  &gt; df1[&quot;c&quot;] # cries again
  [[1]]
  NULL
  </code></pre>
  <p>All I want to see is:</p>
  <pre><code> [[1]]
     c
   1 5
   2 2
   3 9
   4 4
   [[2]]
     c
   1 10
   2 4
   3 18
   4 8
   
  </code></pre>
  <p>Thanks in advance</p>