Daves Redistricting 2.0 Help
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A Typical Scenario
How It Works
The application is a Silverlight 4.0 control running in an ASP page in your browser. When you select a state, the app calls a web service that downloads all of the data you need for that state. Once the app has obtained the data, it never goes back to the server. Also, the app will cache the data on your machine so that you'll get going faster the next time you work on the state. The data includes:
All of the data, except partisan data and custom shapes/data available for a few states, comes from the U.S. Census Bureau.
Note: A block group is a census designation that is a group of up to 4 census blocks. A census block is the smallest area used by the census bureau. Blocks and block groups do not exactly correspond to voting districts or precincts. A voting district is a designation determined by each state. All but a few states have given voting district information to the Census Bureau and the Bureau has computed statistics for those areas. In my application, some states now use voting districts; others still use block groups; and for some I provide both. The size of voting districts appear to vary considerably between states. For some states (e.g. Maryland) I find it harder to get the CDs to have nearly equivalent population, because the voting districts are so populous. For others, they appear very close in size to block groups. For conciseness, in this Help file I will use district to mean block group or voting district.
Note: The polygons and data for states are large and therefore will take time to download. For you techies, to get the polygons, I started with ShapeFiles (.SHP) from the Census Bureau's website. They can be pretty large, so I created my own custom file format (.DSH) that is about 1/4 the size.
The green box is a button labeled "Color Districts." Click the button or double-click on the map to turn coloring on. When coloring is on, the button is labeled "Done Coloring." Hold the mouse button down and sweep the mouse across the map to color districts.
You can also hold down the Ctrl key and the mouse button and move the mouse (called Ctrl-Drag) to draw a box on the map.
When you release the mouse button all the districts in the box will be colored. Click "Done Coloring" or double-click the map to turn coloring off.
Number of CDs
The number of CDs is controlled by the #CDs slider. You can slide the control or use the control's arrows to change the number of CDs you want for your state. Beware: When you change the number of CDs, any districts you have already assigned are cleared. You can create up to 500 "CDs", which allows the application to be used to create legislative districts, too (although there is no provision for loading the old LD polygons).
Color Opacity and Change Colors
The Color Opacity slider allows you to change the opaqueness of the voting districts and old CD shapes. The Change Colors button brings up a panel of colors, allowing you to select any of the colors for any of your CDs.
Simply click on a color and the selected CD changes to that color. Click Done Colors when you're done. Any changes you make will be retained during your current session. You save the current color scheme with the Save to Your Default Colors button; this will keep your color scheme for all future sessions. Reset to Your Default Colors resets all colors to the colors you loaded with the session or the colors you saved with Save to Your Default Colors during the session. Reset to Original Colors resets to the built in color scheme.
The rest of the controls on the left panel are related to CD information. At the top is text showing the state's total population and a Renumber button, which is discussed in detail below.
The remainder of the left panel is a number of rows with information about each CD. Each row contains the following:
Top Control Panel
The top of the application has controls for opening and saving files, selecting a state, showing various shapes and labels, creating area views and more.
The File Menu allows you to save and reload your work across sessions.
New in Daves Redistricting 2.0, you can save your work anywhere you want. The Save As dialog allow you to navigate to any file folder and save your .DRF file. (The app now uses .DRF instead of .DRF.XML, even though the format is still XML.) The .DRF stands for "Daves Redistricting File" and is simple XML to save your work. It does not contain any state information that is loaded from the server.
The app does cache shape and data files that are loaded from the server in Silverlight's obfuscated folders. Also, your old saved .DRF.XML files will still be in these obfuscated folders. Note: the new version of the app may use a different obfuscated folder to save the cached files than the old version used (which is where your old .DRF.XML files will be found).
On Windows, isolated storage is in hidden folders, so you need to tell Windows to "Show Hidden Folders" (from Folder Options) to see them.
When you begin using the new app, a Silverlight dialog box will ask you to approve some 40 or 50 MB for isolated storage. The app asks for a bunch because the data files from the server can be large (they have polygons). By grabbing a bunch of space the application doesn't have to ask again for a while.
The Show section allows you to hide or show county, or old CD boundaries, county names, city and town names, new CD labels and the voting districts themselves. The Old/New CD check box shows the old and new CD boundaries for the selected CD only. Cur CD shows only the currently selected CD. Population by color views the entire state colored according to the percentage of 3 main demographic groups (Black, White and Hispanic); Partisan by color views the state according to partisan data, if available (2008 presidential election). The five check boxes on the right side of the Show section (with background color Bisque): Old CDs, Cur CD, Old/New CD, Population by color, Partisan by color, are mutually exclusive; checking one will uncheck the others.
All labels (county, old CD, new CD, city and town names) are movable, deletable and resizable. When you hover over a label the tool tip tells you how: drag to move, hold the left mouse button and hit delete to delete, and hold the left mouse button and hit 's' or 'l' to make smaller or larger. All labels except city and town names are scaled when zooming.
The Recalc New CD Labels button recalculates the position on the New CD labels. Any changes you have made in size are retained.
In the Area Views section, the Create button creates a view of the current zoomed in area with the current Show choices. You can create up to 70 of these. The Goto Next button allows you to cycle through all area maps. The Goto StateView button goes to the original view of the entire state. The Delete button deletes the current area map.
The Save View JPG button saves the current view as a JPEG. The JPEG does not contain the Bing map in the background, because Bing does not allow its images to be saved.
An alternative to saving a view as a JPEG is to use Print Screen to capture the desired images and then use your favorite photo editor (even Paint) to trim and save into a JPEG or whatever.
Automatically Assigning Districts to CDs
The app has some built-in strategies for automatically assigning districts to CDs. The combo box labeled Auto Assign CDs allows you to choose a strategy. One strategy simply assigns them according to the old CDs.
Another built-in strategy is to split the map into successively smaller quadrants until small enough to begin a CD. Districts in the surrounding squares are then assigned to the CD. This strategy does not attempt to balance the population in the CDs are therefore is simply is a starting point.
New Population Estimates
The base data for the app is the 2000 census data. When you select the Use New Pop Est check box, the app uses newer population estimates. Currently these are 2008 estimates, broken down by county and by ethnicity, from the U.S. Census Bureau. CAUTION: The app distributes the population across all districts in each county commensurate to the population of the districts. Therefore splitting counties among CDs cannot be done precisely.
Find Next Unassigned
Sometimes you may think you've assigned every district to some CD, but the Unassigned population is still non-zero. That means some district is still unassigned. (Some can very small and easy to miss.) The Next Unassigned button cycles through all unassigned districts, panning and zooming to them, to help you find them.
Find CD Parts
Sometimes you may inadvertently leave a small district isolated from the rest of the CD. The Find CD Parts button, finds separate parts of the current CD, so you can make sure to clean them up. It uses the bounding box (rectangle that contains a polygon) to determine if a CD has multiple parts, so it is not guaranteed to find isolated parts of a CD, especially in cases where the CDs are intertwined.
The Bump Quota button allows you to increase the Silverlight quota for cached data files. You can also right-click anywhere on the app to get a Silverlight menu, where you can manage these. Help takes you to this page. How To shows the quick "How To" screen that appeared when you launched the app for the first time. About tells you about the app.
Partisan data, specifically 2008 presidential data, is now supported by the application. See the LaunchApp page for a list of which states are currently supported.
The voting districts shapes and population data come from the 2000 census. Many states changed their voting districts between 2000 and 2008, so the 2008 presidential data does not match completely. For Maryland, for example, over 200 new voting districts were created during that time, so only 1600 of 1800 match the 2000 districts. The application lets you know when this happens and then simply ignores the new districts. This could be improved if someone is able to merge the new districts data back into the old districts.
All states that the Census Bureau provides voting district shapes for, except New York, now support voting districts in the application.
Help Get More Partisan Data
Find out more about partisan data and how you can help get more into the application here.
Changes and Fixed Bugs
Except where noted, the design and implementation of this application was created solely by me.
All of the shapes and data are from the U.S. Census Bureau, except for the partisan data, which was put together by a few other individuals, and the custom "special" shapes and data, which was done by "jeffmd."
The Save View JPG feature uses FluxCore (Copyright 2008-2009 Occipital Open Source) to convert bitmaps to JPEG.
A few features, including assigning districts according to Old CDs, use the Point in Polygon algorithm by Bob Stein.
Thanks. Happy Redistricting! -- Dave Bradlee