title: R: read.table and missing values
body: <p>When I load my data file in tab delimited format in R, I got this error message:</p>
  
  <pre><code>Error in scan(file = file, what = what, sep = sep, quote = quote, dec = dec,  : line 3 did not have 5 elements
  </code></pre>
  
  <p>Here's my data: </p>
  
  <pre><code>KEY ID      code1   code2   name
  1   sadsa   32423   344     ffsadsa
  2   vdffsfs 21344   234     fsadfgg
  3   3e4dsa  21321   #N/A    #N/A
  4   dcxzc   23421   #N/A    #N/A
  5   xzzcc   21223   124     erfsacf
  6   sdas    21321   464     fsadfsa
  7   assdad  32132   455     fsadfda
  </code></pre>
  
  <p>I can see that the error is caused by the "#N/A" value in my data. I have tried the read.table option such as na.strings or comment.char = "#" but it still did not work.</p>
  
  <p>Is there any ways to keep the actual text (#N/A) or at least replace it with N/A when loading the data in R?  </p>