title: Replacing a whole column in R
body: <p>I have searched a lot and I didn't find an answer on this.
  Let's say we have some data from a .csv file(lets call it xx.csv). Something like this</p>
  
  <pre><code>Number  A  B  C ... Z
   1     .. ..  ..
   .
   .
   .
  4000  .. ..  .. ... ...
  </code></pre>
  
  <p>You can put whatever you want in A, B, C,...Names, numbers, NAs etc.
  So, Whats the easiest way that I replace a whole column (lets say B) with another one external (I mean not one from the csv file)??</p>