title: Making a vector from list elements in R
body: <p>I've got a list of lists of bootstrap statistics from a function that I wrote in R.  The main list has the 1000 bootstrap iterations.  Each element within the list is itself a list of three things, including fitted values for each of the four variables ("fvboot" -- a 501x4 matrix).</p>
  
  <p>I want to make a vector of the values for each position on the grid of x values, from 1:501, and for each variable, from 1:4.</p>
  
  <p>For example, for the ith point on the xgrid of the jth variable, I want to make a vector like the following:</p>
  
  <pre><code>        vec = bootfits$fvboot[[1:1000]][i,j]
  </code></pre>
  
  <p>but when I do this, I get:</p>
  
  <pre><code>recursive indexing failed at level 2
  </code></pre>
  
  <p>googling around, i think I understand why R is doing this.  but I'm not getting an answer for how I can get the ijth element of each fvboot matrix into a 1000x1 vector.  </p>
  
  <p>help would be much appreciated.</p>