title: Losing rows of data after converting with as.numeric
body: <p>I have some data, with 8 columns and around 750 rows, read into R with:</p>
  
  <pre><code>    data &lt;- read.csv(file.choose() , header=TRUE)
  </code></pre>
  
  <p>I have created a new dataframe to specify which columns I am using (I will be doing a factor analysis on the data):</p>
  
  <pre><code>    data.TT &lt;- data[ , 16:23 ] 
  </code></pre>
  
  <p>After this, and trying to apply simple arithmetic, I learn that the data is not numeric (it is all integer values). I, therefore, converted the columns to numeric using:</p>
  
  <pre><code>    data.TTn &lt;- cbind( 
              as.numeric(as.character(data.TT$Sociability)),
              as.numeric(as.character(data.TT$Kamplystdrift)),
              as.numeric(as.character(data.TT$Temperament)),
              as.numeric(as.character(data.TT$Forsvarsdrift)),
              as.numeric(as.character(data.TT$Skarphet)),
              as.numeric(as.character(data.TT$Daadkraft)),
              as.numeric(as.character(data.TT$Hardhet)),
              as.numeric(as.character(data.TT$Nervekonstitusjon))
      )
      data.TTn
  </code></pre>
  
  <p>However, I have lost some rows now. I only have around 550 rows versus 750. </p>
  
  <p>Does anyone have any ideas about why this might be? Please let me know if you require more information. </p>
  
  <p>Thanks!</p>