If a polygon is smaller than the largest polygon in our dataset of
simplified polygons then we’re only throwing away useful detail by
simplifying it.
We should still simplify larger polygons as a fallback, to avoid sending
anything to the CBC that we’re not sure it will like.
The thresholds here are low: we can raise them as we test and experiment
more.
Here’s some data about the Flood Warning Service polygons
Percentile | 80% | 90% | 95% | 98% | 99% | 99.9%
-----------|-----|-------|--------|---------|---------|---------
Point count| 226 | 401.9 | 640.45 | 1015.38 | 1389.07 | 3008.609
Percentile | 80% | 90% | 95% | 98% | 99% | 99.9%
--------------|-----|-------|--------|---------|---------|---------
Polygon count |2----|3------|5-------|8--------|10-------|40.469
We don’t support these methods at the moment. Instead we were just
ignoring the `msgType` field, so issuing one of these commands would
cause a new alert to be broadcast 🙃
We might want to support `Cancel` in the future, but for now let’s
reject anything that isn’t `Alert` (CAP terminology for the initial
broadcast).
Other systems we’re working with won’t easily be adapted to emit JSON
instead of CAP, so it’s less work for us to do that conversion.
This commit adds to code to parse the XML and turn it into a dict that
we can work with, including converting the polygon string into native
Python lists.
