title: change value to percentage of row in R
body: <p>this is my data</p>
  
  <pre><code>  A B C
  A 9 1 0 
  B 2 2 2
  C 3 3 3
  </code></pre>
  
  <p>I want to get percentage of each row</p>
  
  <p>my expect data is</p>
  
  <pre><code>     A    B    C
  A  0.9  0.1    0 
  B 0.33 0.33 0.33
  C 0.33 0.33 0.33
  </code></pre>
  
  <p>I made my data with 'dcast' and there is column name on A,B and C.
  so actually my real data is </p>
  
  <pre><code>  Name    A    B    C
  1    A  0.9  0.1    0 
  2    B 0.33 0.33 0.33
  3    C 0.33 0.33 0.33
  </code></pre>