title: Importing data from multiple csv files in D3
body: <p>I am brand new to D3 and just started working on an a project. My question is this.
  I want to import data from 2 csv files in D3 to use them for graph comparisons. The problems I am facing are:
  <p> 1.How do I import data from multiple csv files.<br>
  2.Can I use one array for each csv or does D3 use only one global data array?<br>
   3.Is there a way to choose a certain column from the csv files to import?<br>
  <br>Here is an example, I want to import the "oldVer" from each of the files in separate arrays and then use the 2 arrays to work with. Is that posible in D3 and how?</p>
  
  <p>csv 1<br>
  time,oldVer,newVer,oldT,newT<br>
  1,180930,190394,24,59<br>
  2,198039,159094,26,45<br>
  3,152581,194032,22,61<br></p>
  
  <p>csv 2<br>
  time,oldVer,newVer,oldT,newT<br>
  1,184950,180435,27,26<br>
  2,120590,129409,13,13<br>
  3,165222,182133,60,54<br></p>
  
  <p>Again sorry for the dumb question but I have found little feedback on this matter. Any help will be appreciated.</p>