Feature: On-the-fly aggregation for a custom polygon

[chriswhong]

It would be great to allow the user to draw a polygon on the map and then generate a simple report/bar chart of the sidewalks with percentages for the four groupings.

Maybe you could show a chart with borough aggregates by default, allow the user to specify a custom study area.

In addition to the great visual, this will give users some hard numbers to take to their elected officials, tweet out, etc. "60% of sidewalks in my neighborhood are too narrow for safe social distancing"

[meliharvey]

These are great ideas that I've heard echoed in other people's responses. It seems like boroughs, and something smaller like neighborhood tabulation areas or zip codes would be most helpful for some summary statistics. I'm going to think about how these could be integrated into the UI.