title: Sum all values in every column of a data.frame in R
body: <p>Given this data set:</p>
  
  <pre><code>  Name Height Weight
  1 Mary     65    110
  2 John     70    200
  3 Jane     64    115
  </code></pre>
  
  <p>I'd like to sum every qualifier columns (Height and Weight) yielding</p>
  
  <pre><code> 199  425
  </code></pre>
  
  <p>The problem is that the qualifiers can be more than just 2 (i.e. more
  than just Height and Weight).</p>
  
  <p>I can do this.</p>
  
  <pre><code>    # Create the dataframe people
      Name &lt;- c("Mary", "John", "Jane")
      Height &lt;- c(65,70,64)
      Weight &lt;- c(110,200,115)
      people &lt;- data.frame(Name, Height, Weight)
  
      res &lt;- c(sum(people$Height),sum(people$Weight))
  </code></pre>
  
  <p>But it gets too long when the qualifier increase.
  What's the compact way to do it?</p>