title: save multiple graphics in svg
body: <p>Assuming this script that generates two generic graphics "a" and "b"    </p>
  
  <pre><code>library(ggplot2)
  
  # dataset:
  data=data.frame(value=rnorm(100))
  
  # basic histogram
  a &lt;- ggplot(data, aes(x=value)) + 
    geom_histogram()
  
  a
  
  # dataset:
  datab=data.frame(value=rnorm(70))
  
  # basic histogram
  b &lt;- ggplot(datab, aes(x=value)) + 
    geom_histogram()
  
  b
  </code></pre>
  
  <p>How to save the "a" chart and the "b" chart in two different files in .svg format with the size I determine. here I simulated two graphs, but I have 12 and I would like to optimize the process in a script, instead of using the export button on each one.</p>