title: How to source file.R without output
body: <p>Is it possible to source a file without printing all the charts etc (already tried with echo=F)? </p>
  
  <p>In my case I call the png("filename%03d.png") device early in the script. It is not to big a hassle to comment this out - but all the charts do take a lot of time to render. (the specific file I am working with now uses base-graphics - but mostly I'll be using ggplot2 - which makes the issue somewhat more important (ggplot2 is excellent, but in the current implementation not the fastest))</p>
  
  <p>Thanks</p>