title: Unable to determine what type of blank, null, na or anything else in R dataframe
body: <p>I have a data frame loaded from an Excel csv. One columns has many &quot;NULL&quot;. This is what is showing up when looking at the data in RStudio. When I filter in the RStudio viewer by typing in NULL it gets over 13,000 rows. I've been trying to do the same in code with no luck. I've tried.</p>
  <pre><code>newSurvey %&gt;%
    filter(is.null(TextAnswerValue))
  </code></pre>
  <p>Zero values</p>
  <pre><code>newSurvey %&gt;%
    filter(is.na(TextAnswerValue))
  </code></pre>
  <p>Two values</p>
  <pre><code>newSurvey %&gt;%
   filter(TextAnswerValue == &quot;&quot;)
  </code></pre>
  <p>Zero values</p>
  <pre><code>newSurvey %&gt;%
    filter(length(TextAnswerValue) &lt; 10)
  </code></pre>
  <p>Zero values</p>
  <pre><code>newSurvey %&gt;%
    filter(TextAnswerValue) == NULL)
  </code></pre>
  <p>Zero values</p>
  <p>Nothing works, not sure what else to try.</p>