title: Create adjacency matrix calculate distance between many city
body: <p>I am currently have a data like this</p>
  
  <pre><code>                   0                     1        2
  0   Ho Chi Minh City               Dalat   1146.72
  1  Ho Chi Minh City               Mui Ne    220.00
  2  Mui Ne                         Dalat    340.00
  </code></pre>
  
  <p>I want to create a matrix that can display double array like</p>
  
  <pre><code>                     HCM                Dalat        Mui Ne
      HCM               0                 1146.72       220
      Dalat             1146.72           0             340
      Mui Ne            220               340           0
  </code></pre>
  
  <p>There are more cities in my datafarme. I can understand the adjacency matrix, however I don't know how to display to the adjacency matrix, and code can understand that HCM to HCM is 0.</p>