r - Dynamic choropleth, with time slider or auto playing -

i trying replicate this map:

http://darkhorseanalytics.com/blog/wp-content/uploads/2014/05/nybreathe.gif

which alternates showing housing , employment densities in nyc through day, in r.

i have spatial object, s, census small area polygons , 2 variables, inhabitants (s@data$pop) , employment (s@data$emp), each area.

as in example, have 2 "extreme" cases:

1. choropleth of s@data$pop, in blue, dominant @ midnight.
2. choropleth of s@data$emp, in red, dominant @ noon.

and 'intermediate' plots make smooth transition between "1." , "2.".

and result "auto play", e. i., keep repeating cycle between "1." , "2.".

i imagine ggplot2 + shiny, having time slider control time of day. , perhaps somehow automate, or autoplay time variable. doable in shiny (or other r solution)?