title: Producing a new dataframe from an old dataframe?
body: <p>I want to produce a <code>new</code> dataframe from an <code>old</code> big one (many variables)
  I use the <code>cbind.data.frame</code> function and it goes like this</p>
  
  <pre><code>new &lt;- cbind.data.frame(old$var1, old$var2, old$var3)
  str(new)
    'data.frame': 100 obs. of  3 variables:
  $ old$var1        : num
  </code></pre>
  
  <p>Why does the var1 still belong to <code>old$</code> ?<br>
  I wanted to use just <code>new$var1</code> but it returns <code>object not found</code>.</p>
  
  <p>What am I doing wrong?</p>