title: Applying a function to every row of a table using dplyr?
body: <p>When working with <code>plyr</code> I often found it useful to use <code>adply</code> for scalar functions that I have to apply to each and every row.</p>
  
  <p>e.g.</p>
  
  <pre><code>data(iris)
  library(plyr)
  head(
       adply(iris, 1, transform , Max.Len= max(Sepal.Length,Petal.Length))
      )
    Sepal.Length Sepal.Width Petal.Length Petal.Width Species Max.Len
  1          5.1         3.5          1.4         0.2  setosa     5.1
  2          4.9         3.0          1.4         0.2  setosa     4.9
  3          4.7         3.2          1.3         0.2  setosa     4.7
  4          4.6         3.1          1.5         0.2  setosa     4.6
  5          5.0         3.6          1.4         0.2  setosa     5.0
  6          5.4         3.9          1.7         0.4  setosa     5.4
  </code></pre>
  
  <p>Now I'm using <code>dplyr</code> more, I'm wondering if there is a tidy/natural way to do this? As this is <strong>NOT</strong> what I want:</p>
  
  <pre><code>library(dplyr)
  head(
       mutate(iris, Max.Len= max(Sepal.Length,Petal.Length))
      )
    Sepal.Length Sepal.Width Petal.Length Petal.Width Species Max.Len
  1          5.1         3.5          1.4         0.2  setosa     7.9
  2          4.9         3.0          1.4         0.2  setosa     7.9
  3          4.7         3.2          1.3         0.2  setosa     7.9
  4          4.6         3.1          1.5         0.2  setosa     7.9
  5          5.0         3.6          1.4         0.2  setosa     7.9
  6          5.4         3.9          1.7         0.4  setosa     7.9
  </code></pre>