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DavesRedistricting New Features

by: dgb

Sun Jul 12, 2009 at 6:27 PM EDT


First, let me say that I'm impressed by the many redistricting maps many of you have created recently. I'm happy that you have found my application useful. It's been fun working on it and it makes it so worthwhile to see what you all are doing with it.

Today I uploaded an updated application with these new features, all of which are requests from those of you who have emailed me. They are...
dgb :: DavesRedistricting New Features
-- A button to assign all blocks according to the old CDs, so you can start your map with the current map and save time.
-- Up to 500 CDs, so you can use the app for legislative districts, too. (Although there are no old LD polygons...yet.) The selection of #CDs is now a slider instead of a dropdown.
-- Demographic info bar (at the bottom of the app's screen) now has percentages, as well as the number of persons in each demographic group. Also, hover on the state population text block and get the demographics for the state.

Also, Pennsylvania is officially there now. (Actually the data has been there for a month; my apologies for not announcing sooner.)

Next up: adding NY and IL; and figuring out how to add partisan data. (DavidNYC has been assisting. Thanks!)
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DavesRedistricting New Features | 38 comments
Hey Dave
Thanks for putting this up. This will prove to be very useful, I think.

Two issues I notice off the bat:

1. I'm starting with Pennsylvania, because I know it best. When I specify 18 districts, and then choose the draw the old ones, the old 19th is the one left out. But one concern I have is, what if I'd rather cut out a different district (say the old 15th)? An active choice to say, for example, "draw old 8, and number it 18" would be useful (if more complicated!)

2. I notice that the old districts are not contiguous. I assume this is because te census bloc lines don't line up perfectly.

Otherwise, this is an impressive improvement to what you already have. Thanks!  

One positive improvement
is that the population counts pop up much more quickly and reliably on mouseover than before.  
[ Parent ]
Good points
To deal with the first would require additional input from the user to say which district(s) to leave out. More work (and compilcation for the user). But I will think about this.

On the second point, it is both because I'm using larger blocks (block groups), which can get split, and because Pennsylvannia is so egregiously gerrymandered, so there are lot's of little corners that may get misplaced. If you show the old CDs, you'll see where the app missed.

Thanks!

[ Parent ]
thanks personally for your software.
Great improvement. I don't know if I email you but I did have several suggestions that would make redistricting states with huge urban areas much easier. Such as Texas, there is obviously a big focus on creating hispanic and aa seats, but some of these urban areas are huge and the minorities aren't in general areas but sort mixmatched and it makes it very frustrating to try and draw them in. Having a feature that would highlight majority hispanic or majority black precincts would be a huge help those instnaces.

Beyond that I ws thrilled to learn that David nad jeffmd are working with you to add political data to the mix because most of the time I've found the data needed to be either non-existant, or fharged for a fee, or simply not in a form that is feasible to use.

Call no man happy until he is dead-Aeschylus

[ Parent ]
Good suggestion
It shouldn't be too hard to highlight those somehow. I'll think about how to do that. Thanks.
[ Parent ]
thanks, I really have
no right to criticize, I should merely get on my feet and worship the ground you walk on for making it so much easier. No long did I have to use microsoft paint, and use a calculator and wikipedia to count the poulation of every county in a district and be completely stumped when it came to cities. Its like trying to make a computer with a piece of rock and a chisel :P

Call no man happy until he is dead-Aeschylus
[ Parent ]
quick objection
It would be nice if the white color that's used for district 56, 112, etc. is changed, because it's really hard to work with.
Good catch
That's a bug. I'm doing Mod 56, so 56 is the same as 0 and 0 is white (no CD assigned). I will fix that hopefully in a couple of hours. (It should only take a few minutes, but it's almost dinner time!)

Thanks.

[ Parent ]
not able to open old saved files
the only problem I'm having with the new version

26, male, Dem, NJ-12
I'm not hing that problem


Call no man happy until he is dead-Aeschylus
[ Parent ]
Looks like a bug
Sounds like it can't read the file, right? Do you get the error message "GeoID2 strings don't match"?

It looks like a bug. I have to look into this further, but I can repro it with a Minnesota file I saved a couple of months ago. Sometimes there are these duplicate districts (2 districts in the census data file with the same GeoID) and I must have done something to change the order of those in the file. It may only happen with certain states, which is why some people don't hit it.

I will try to fix it, but it may take me a day or two (as I have other commitments).

Thanks for letting me know.

[ Parent ]
GeoID2 strings don't match
That's the one.

26, male, Dem, NJ-12
[ Parent ]
It must be difficult to add partisan data
because your map goes by block group, which doesn't match up with precincts.  You would almost have to switch to precinct or combined precincts, right?  I'm glad you added more possible distrricts, because I was wanting to try to redistrict the Michigan State House.

16, Male, MI-01
Partisan data
I'm trying to figure out how to handle this without going to precinct level. We'll see. It could be tricky, but I think, with DavidNYC's help we can come up with a solution.
[ Parent ]
ETA on Alabama?
just curious.  thanks for all your work.
Some useful stuff in this update.
But i would like to encourage you to add Wisconsin soon. As i really would enjoy playing around with my state.

20, male, independent, WI-07.
I hope California will be up soon. eom


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28, New Democrat, Female, TX-03 (hometown CA-26)
Other states
Not sure after NY and IL, but if you all ask for them, I'll bump them up the list.  Thanks!
AL and MS eom

[ Parent ]
Colorado
if you can do that, that would be amazing
[ Parent ]
I second that
I'm looking forward to a Colorado map I already have in my head.  That said, Dave, would it be possible to add landmarks into the census block groups (highways, major streets) as an overlay grid. I'm trying to draw a downtown C-Springs to Manitou and Old Colorado City district that's competitive and, in a good year, lean D.  To do that, I can't go anywhere north of Woodman Road and I-25. If I do, I get into the crazy parts of town. Problem is, with the census blocks the way they are, I can't know where Woodman actually is. Any idea on how to get around this?

30, male, Democratic, CO-01
[ Parent ]
Haven't found anything that works
I tried this a while back, but I need a shapefile for the state with that info in it or an image that can be fit. I looked around but couldn't find anything. One way might be to integrate Google maps into it, but that a big project.
[ Parent ]
Okay
I just thought of a cheaters way: Rep. Merrifield's House District and SD-11 roughly cover the territory I need, so I guess I can fake it from there.

30, male, Democratic, CO-01
[ Parent ]
California
and Virginia.

Call no man happy until he is dead-Aeschylus
[ Parent ]
Virginia and Alabama would be nice

[ Parent ]
Maryland!


26, male, Dem, NJ-12
[ Parent ]
CA, VA, and MD


21, Male, Democrat, MD-02 (home/registered), MD-05 (college)
[ Parent ]
Virginia!
Also Colorado.

Thank you so much for this wonderful tool and all the work you have put into it. I love it!  

[ Parent ]
California!


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Twitter
Scribd
28, New Democrat, Female, TX-03 (hometown CA-26)
[ Parent ]
VA and MD
But I can't wait for IL.
[ Parent ]
2 Bugs Fixed!
I fixed the 2 bugs you all found today:
(1) Color 56 is no longer white (same as color 0, which is unassigned). Now I don't reuse that color
(2) Fixed problem loading older saved files. Essentially I was expecting the order of the blocks to be the same. (I order them based on distance from the upper left corner (0,0).) But in the census bureau data, some blocks had center points that were not specified. They had been default to (0,0), but I had changed that to use the bounding box for the polygon, so the Assign Old CD feature would work. And that changed the order! This is a bad bug, so I got a fix quickly.

Thanks for catching these. Let me know if you find more bugs.

Awesome!
Thanks for fixing it.

26, male, Dem, NJ-12
[ Parent ]
States I would like to see next are
California!!! My home state and it would be nice to see Virginia and Maryland too. Also, do you know how soon you will have NY and IL up? Thanks.

for more election analysis, visit  http://frogandturtle.blogspot....




17, CA-06,  

NY
Possibly Sunday. If not then the following Saturday or Sunday.
[ Parent ]
Will the new census blocks be added before or after the Census?
It's hard to work with these explosively growing Georgia counties like Forsyth and Paulding when the blocks have 15,000 people.

Follow the elections in Georgia at the 2010 Georgia Race Tracker.
Census Bureau will add blocks
I think that in preparing for the census, the bureau will add new blocks to accomodate that growth, But I don't know if they will republish old data against the new blocks. I'm not exactly sure how they make those decisions.
[ Parent ]
A feature I would like
Is showing town lines for Massachusetts (and presumably the rest of New England.) We don't use counties here for anything, they're just a historic geographic designation and towns are the base political unit.  (There are no "unincorporated" areas in the state.)  Obviously you'd want to make the lines fairly thin, since there are 351 cities and towns in total, but currently I have to use a separate map with town lines and cross referencing can be confusion.

28, Unenrolled, MA-08
Demographic percentages for census blocks
It would be helpful to have those added, especiallly for areas that are very diverse with strong representation from more than two ethic groups.

Follow the elections in Georgia at the 2010 Georgia Race Tracker.
DavesRedistricting New Features | 38 comments

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