title: as.factor() in numeric conversion R
body: <p>So I am learning R now, and I notice from many source that whenever we want to convert a datatype to numeric,we use two functions <code>as.numeric()</code> and <code>as.factor()</code>.</p>
  
  <p>For example if I want to convert column Year to numeric, it will be</p>
  
  <pre><code>as.numeric(as.factor(survey.data$Year))
  </code></pre>
  
  <p>I tried to use <code>as.numeric()</code> alone and it works perfect as well. But I feel there is sth I am missing out in this way. I am just wondering what is the reason to first convert to Factor , then to Numeric?</p>
  
  <p>Thanks.</p>