Plotting side-by-side bar graph

Instead of stacking the categories, we could have chosen to display them side-by-side. You might recall one side-by-side bar graph coming from a blog, magazine or newspaper. These plots can be easily made with ggplot2 and plotly, but  ggvis was not there when this book was written. Check the See also section for more reference.

This kind of viz is good to show comparisons between categories across some other categories (or time). If you choose side-by-side bars instead of stacked ones you're probably choosing to highlight the variable displayed by colors over the one displayed by the x-axis. Let's see how ggplot2 and plotly handle it.

Getting ready

Besides the usual ggplot2 and plotly packages, car package is required once data frame is coming from it. We also need plyr to do some computation:

> if( !require(car)){ install.pacakges('car')}
> if( !require(plyr)){ install.packages('plyr')}

Running the preceding code is going to check local availability of such...