This is NOT what democracy looks like!

[angledge]

Ha ha! Data processing is finally finished for the 108th Congressional district map of Pennsylvania. 480,979 census blocks, sorted into 19 Congressional districts. Now that my data is in place, time to start getting the algorithms running ....




Here's a GIF, created in MS Paint from a TIFF exported from ArcMap.


Here's a PNG, created in MS Paint from a TIFF exported from ArcMap.

Comments

Ah ha.

[angledge.livejournal.com]

Good to know. What's the highest quality graphics format webpages can utilize?

Re: Ah ha.

[marasca.livejournal.com]

Best format depends on what's in the graphic. For blocks of color, lines, text, etc, GIF usually works best. The lines will be crisp and file size relatively small. For photos or graphics with a lot of shading (like a drawing), JPG will work better than a GIF.

I think most browsers can use PNG format, but most people don't use those for some reason. I'm not sure if the quality or file size on PNGs is better or worse than JPGs.

Re: Ah ha.

[d4b.livejournal.com]

I agree that GIF will be best for this. What intrigued me is that this particular graphic auto-sizes; I've never seen that. (i.e., It changes based on the size of the browser window.) That's why some of the lines and text have alternate widths.

For best results, start with an image that's 4x the final size on each side, and make sure you have as many colors as possible when you reduce it down by 25%.

just for local interest

[angledge.livejournal.com]

Here's a closeup of the Jenkintown area. I especially like the strange appendage of District 8 that snakes down from Bucks County into Upper Dublin township. Also, notice that the tiniest bit of the Southwest corner of Jenkintown is in District 2.

Re: just for local interest

[krick.livejournal.com]

Do the boandary lines follow rivers or roads? That might explain some of the strangeness.

Re: just for local interest

[krick.livejournal.com]

It just occurred to me that they might be following zip code boundaries.

In auto insurance, the whole state is divided into "territories" that are gerrymandered by the insurance industry to group highest risk areas together. In Pennsylvania, this results in things like this description of what comprises territory 01:



It's almost impossible to know what territory you live in. Imagine you were planning to buy a house and wanted to live in one of the "cheaper" territories. Good luck.

In California and a few other states, the people got fed up with this crap and made them change it all to a zipcode based system. As a result, boundary lines are a bit jagged.

Re: just for local interest

[angledge.livejournal.com]

The lines generally follow the boundaries of the census blocks. But they do so with discretion - after all, there are 480,000+ blocks & only 19 Congressional districts. So, which blocks get placed into which Congressional districts? That's the heart of the gerrymandering exercise. Gerrymanders use Census data & GIS software to tailor-make districts with certain characteristics - they use data such as previous voting results, party registration lists, even stuff like magazine subscriptions to guess how many Democratic/Republican voters live in each Census block. Then they group together Census blocks to give their party the competitive advantage.

Re: just for local interest

[d4b.livejournal.com]

Thanks! I'm having trouble finding an appropriate political map to match up details, but from what little I can derive, it'd seem that Jenkintown's borders themselves might be a bit of similar manipulation. Maybe I'm too cynical, but... that little bump in the SW corner would seem to correspond with that private bank (whose name escapes me at the moment) which only has a few hundred clients, but each one meeting their $5 million minimum account requirements (or did they poor-down recently and drop it to $2MM?). You probably know of the institution of which I speak; it's essentially a private bank primarily for the Pitcairn family. If my hunch is true, Jenkintown would get the corporate taxes, but Cheltenham would "get" the votes (not that anyone actually lives at the bank, so it's a non-issue). Similarly, that little bump on the SE corner is probably the Pavillion, although I always thought that that was in Abington township and only a Jenkintown mailing address. Again, that'd seem to be a huge tax revenue source.

Re: just for local interest

[angledge.livejournal.com]

Re-adding the graphic after the linky broke:

Re: Ah ha.

[krick.livejournal.com]

That "auto-sizing" is a "feature" of Internet Explorer 6. Images larger than your maximized browser window will resize themselves to fit on the screen. I think the feature sucks. There is some way to turn it off but I forget how.

Re: Ah ha.

[d4b.livejournal.com]

Yes, I know of what you speak; I've seen the little circle-with-arrows thingie in the lower-right corner of images that MSIE decided it could distort. But this was different, and also didn't offer that thingie. It was almost as if the graphic was defined by rasters rather than pixels.