Stats-driven lens shopping with Ruby

I developed the script photo_stats.rb to move through date-based folders of photos, and grab EXIF data (thanks to the exifr gem) for each photo. The script calculates the mean focal distance of all the photos, sums photos at the widest focal distance (18mm), maximum distance (200mm), and those in the bottom (18.0-46.0mm) and top (154.0-200.0mm) quarter of the focal range.