title: Finding row index containing maximum value using R
body: <p>Given the following matrix lets assume I want to find the maximum value in column two:</p>
  
  <pre><code>mat &lt;- matrix(c(1:3,7:9,4:6), byrow = T, nc = 3)
  mat
       [,1] [,2] [,3]
  [1,]    1    2    3
  [2,]    7    8    9
  [3,]    4    5    6
  </code></pre>
  
  <p>I know <code>max(mat[,2])</code> will return 8. How can I return the row index, in this case row two?</p>