hey, i've been trying to recreate your bubble chart visualization, thanks for going through it so clearly! however i still managed to break something despite your thorough explanation.

i downloaded all of your sources files but when i run a simple server on my end i get the following errors over and over:

Error: Invalid value for attribute r="NaN"

the circles are all visible and sized correctly, so i know they're getting the data, but they're collapsed on top of each other. any idea what i'm doing wrong? I'm a bit confused since i just copied your files directly, i haven't altered anything yet.

I came across your excellent recreation of the city demographic visualization and thought the visualization could take advantage being displayed on a computer.

When looking at the data it was difficult to determine how amount of Irish in Boston compared to Cleveland. So I added the ability to click on a demographic and just see that demographic across the cities.

It's in a repo here: https://github.com/vrish88/vis (sorry for the strange githubness... it just felt awkward forking your private blog).

Also, as a complete n00b to making visualizations any feedback is gladly welcomed.