title: Calculate percentages across rows using dplyr/plyr?
body: <p>I have a dataframe x, like this. </p>
  
  <pre><code>set.seed(1)
  x &lt;- data.frame(id = letters[1:3], c1 =runif(3,max=3), c2 = runif(3,max=2), c3 = runif(3,max=4))
  
  # id        c1        c2        c3
  # 1  a 0.3271498 1.8415800 0.3496333
  # 2  b 1.4744138 1.3157962 1.9983840
  # 3  c 2.6475328 0.8444028 3.9316721
  </code></pre>
  
  <p>I want to be able to calculate percentages across each individual row using dplyr, or another tidyverse package. Any ideas? </p>
  
  <p>For instance, the output of x would be: </p>
  
  <pre><code># id        c1        c2        c3
  # 1  a 0.1299057 0.7312607 0.1388336
  # 2  b 0.3079012 0.2747772 0.4173217
  # 3  c 0.356637 0.1137456 0.5296174
  </code></pre>
  
  <p>Thanks for taking the time. </p>