title: Error counting non-NA entries in dataframe
body: <p>I am trying to see if the amount of information that I have about a case is correlated to the duration of the user.</p>
  
  <p>Currently, I have a dataframe, df, and I attempted to do the following:</p>
  
  <pre><code>df["amount_known"] &lt;-df[rowSums(!is.na(df)),]
  </code></pre>
  
  <p>This resulted in the following error:</p>
  
  <blockquote>
    <p>Error in <code>[&lt;-.data.frame</code>(<code>*tmp*</code>, "amount_known", value = list(status = c(3L,  : 
      replacement element 1 has 808047 rows, need 808247</p>
  </blockquote>
  
  <p>What could cause this to happen (and of course, how do I fix it)?</p>