R Markdown only shows the result display.

I studied with R Markdown and came across this question. All reproducible sample reports that I found on the Internet, such as http://jeromyanglim.blogspot.ca/2012/05/example-reproducile-report-using-r.html , have code followed by the result.

I want to have only the result, so I hide the code from the audience. For example, I would just like to show the end result of ggplot2 or googlevis without showing long lines of download and encoding data.

Is there any way to do this?