title: Combining two csv's (d3)
body: <p>I am loading two csv files using the following code</p>
  
  <pre><code>    d3.csv("sqrt100train.csv", function(error, data2) {
      d3.csv("sqrt100test.csv", function(error, data) {
  </code></pre>
  
  <p>sqrt100train looks like this:</p>
  
  <pre><code>    Trees   Train
      1   0.059286
      2   0.057857
      3   0.032857
      4   0.03619
      5   0.022619
  </code></pre>
  
  <p>and sqrt100test looks like this:</p>
  
  <pre><code>    Trees   Test
      1   0.072222
      2   0.072778
      3   0.044444
      4   0.049444
      5   0.042778
  </code></pre>
  
  <p>How do I combine these arrays to get this:</p>
  
  <pre><code>    Trees   Train   Test
      1   0.059286    0.072222
      2   0.057857    0.072778
      3   0.032857    0.044444
      4   0.036190    0.049444
      5   0.022619    0.042778
  </code></pre>