Add what districts they touch

[timwis]

Which council/state rep districts (and who the rep is) and what percentage of the ward or district it makes up

[timwis]

From @andrewbt:

OK, so here's a council district:

https://team.cartodb.com/u/athompson/tables/athompson.council_district/public/map

Here's a ward leader that overlaps that district but not entirely:

https://team.cartodb.com/u/athompson/tables/athompson.ward_leader/public/map

Run this SQL on the ward_leader table:

SELECT ward_leader.cartodb_id, st_intersection(ward_leader.the_geom_webmercator, council_district.the_geom_webmercator) as the_geom_webmercator
FROM ward_leader, council_district
WHERE st_intersects(ward_leader.the_geom, council_district.the_geom)

And you get this result:

https://team.cartodb.com/u/athompson/tables/athompson.council_district_owned_by_ward_leader/public/map

You can use PostGIS to calculate the area of the result, the area of the council district, and divide the two:

http://docs.cartodb.com/tips-and-tricks.html#calculate-area-of-a-polygon

We only have to do this once, as it only changes every 10 yrs with redistricting

[timwis]

Thought about this some more and it's really not about surface area; it's about the number of voters. Given that divisions are roughly based on the number of voters within them (I believe), we could base this on the number of divisions within each district. Probably changes the math a bit, but worth it I think.

[andrewbt]

Yeah, I mean, don't divisions nest evenly into council districts? Then it's
pretty easy.

If divisions, as the smallest political geography in the city, don't nest
evenly with every other political geography , that makes me want to amend
the Home Rule Charter or something.

On Sun, Apr 5, 2015 at 11:13 PM, Tim Wisniewski [email protected]
wrote:

Thought about this some more and it's really not about surface area; it's
about the number of voters. Given that divisions are roughly based on the
number of voters within them (I believe), we could base this on the number
of divisions within each district. Probably changes the math a bit, but
worth it I think.

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Andrew Thompson, Sales Engineer

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[timwis]

They do! 99% positive. Can you elaborate on the "easy" part? :P

[datadan0]

Tim, I just committed two CSV's to the project. Let me know if that is what you are looking for or if I should make changes.

[timwis]

Awesome, thanks Dan!! I'll take a dive in at Code for Philly this week and get them on the app. Great work. link for quick access

[datadan0]

No problem. Glad to help out! I just added shapefiles and other files I
used to prepare the final tables. I wasn't sure what format you preferred
so the final tables are sort of like samples. I don't think I will be able
to make the next session, but let me know how you prefer the tables and I
am happy to adjust. Also, let me know if you want me to join the final
Ward table to the original Ward shapefile. I think it might be cool to
show the information on a map too. We could probably do it on google maps
or cartodb. Have a good Sunday!

On Sat, May 9, 2015 at 2:09 PM, Tim Wisniewski [email protected]
wrote:

Awesome, thanks Dan!! I'll take a dive in at Code for Philly this week and
get them on the app. Great work. link for quick access
https://github.com/Ruprict0/philly-ward-leaders/tree/gh-pages/data

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