title: extract data from a list without using loop in R
body: <p>I have a vector v with row positions:</p>
  
  <pre><code>v&lt;-c(10,3,100,50,...)
  </code></pre>
  
  <p>with those positions I want to extract elements of a list, having a column fixed, for example lets suppose my column number is 2, so I am doing:</p>
  
  <pre><code>data&lt;-c()
  data&lt;-c(list1[[v]][[2]])
  </code></pre>
  
  <p>list1 has the data in the following format:</p>
  
  <pre><code>[[34]]
        [1] "200_s_at" "483"        "1933"        "3664"        
  </code></pre>
  
  <p>So for example, I want to extract from the row 342 the value 1910 only, column 2, and do the same with the next rows</p>
  
  <p>but I got an error when I want to do that, is it possible to do it directly? or should I have a loop that read one by one the positions in v and fill the data vector like:</p>
  
  <pre><code>#algorithm
  for i&lt;-1 to length(v)
      pos&lt;-v[i]
      data[[i]]&lt;-c(list1[[pos]][[2]])
  next i
  </code></pre>
  
  <p>Thanks</p>