Is there a plot library for R that could turn a dataframe of start and stop times  into a timeline plot something like the following:

![enter image description here][1]

So the Y axis doesn't have any meaning (it just stacks with concurrency). Each grey box is an event -- a row from the dataframe. The dataframe would have two columns, a start time and a stop time.


  [1]: https://i.sstatic.net/OKv3q.png