Plotting “time of day” data using ggplot2

William asks:

How can I make a graph that looks like this, “tweet density” style, showing time intervals?

He then helpfully describes his input data: a CSV file with headers “time started, time finished, date”.

RSRuby and Rails revisited

A couple of months ago, I wrote a brief guide to displaying R plots in a Rails application using RSRuby.

It worked at the time – really it did – but since then, I’ve encountered problems. One is that despite sending the plot output to a PNG file, R X11 windows started to pop up on loading the web page containing the plot. Another is the appearance of long error messages related to “stack smashing” on terminating Mongrel server.

Fortunately, I read an excellent guide by Ana Nelson, R on Rails with RSRuby, which convinced me that I was doing things all wrong. So here is an amended version of my R + RSRuby + Rails “Hello World” application.