title: Unexpected Symbol in As Formula, Can't Find
body: <p>I've been using <code>as.formula</code> for setting up a glm, and I can't figure out where the unexpected symbol is. Part of the problem is that the character vector I'm converting is so long. It's about 700 words with <code>+</code> inserted in between in order to turn it into a formula. The error presents as follows:</p>
  
  <pre><code>Error in parse(text = x, keep.source = FALSE) : 
     &lt;text&gt;:2:10080: unexpected symbol
  </code></pre>
  
  <p>with the following snippet of the text:</p>
  
  <pre><code>2: c_1_E + Campaign_Search_Payroll_Generic_1_P + Campaign_Search_Performing_Core_Keywords + Campaign_Self_Employment_E + Campaign_Self_Employment_P + Campaign_Withholding + Campaign_Youtube + Sou
  </code></pre>
  
  <p>Things I know for sure:</p>
  
  <ol>
  <li>No item is repeated.</li>
  <li>No symbols other than alphanumerics and underscore (<code>_</code>).</li>
  <li>No item starts with a number.</li>
  </ol>
  
  <p>I'm not well versed enough in R to understand reading the documentation for <code>as.formula</code> or the function call itself.</p>
  
  <p>Any ideas?</p>