title: Selecting with dplyr by variable name, some column names are numbers
body: <p>I want to select column names by passing a vector argument to dplyr's select:</p>
  
  <pre><code>df &lt;- data.frame("A" = letters[1:5], "B" = letters[6:10], "2015" = rep(1, 5), check.names = F)
  vars &lt;- c("A", "2015")
  select_(df, .dots = vars)
  Error: Position must be between 0 and n
  </code></pre>
  
  <p>I think it interprets column <code>2015</code> as a number and fails because there are only three columns in <code>df</code>. Is there a way of select both columns without renaming column <code>2015</code> to something like <code>X2015</code>? </p>