title: create data table using for loop
body: <p>let's say I have a <code>data.table</code></p>
  
  <pre><code>DT=data.table(name = sample(letters[1:25],30,replace=T), value =rnorm(3000)) 
  </code></pre>
  
  <p>I want to split the <code>DT</code> by names and create new DTs like name <code>DT_a</code>,<code>DT_b</code> corresponding to the name value. So how could I do it?</p>