[Qgis-user] Breaking a territory into zones

[Thayer Young]

 Hi Jason,
First to answer Nicolas' question, US Census blocks are polygons, they are the smallest published unit of the US Census, they are designed to be roughly equal in population (very rough in some places), so they vary drastically in size and shape.
To not reinvent the wheel I would suggest that you search the literature for election redistricting. I think you should be very careful about trying to split census blocks into finer units. But some states like Maryland do have estimates of the number of dwelling units per parcel.
This is a recent blog post about using R for computational redistricting:https://www.r-bloggers.com/2021/02/some-computational-redistricting-methods-or-how-to-sniff-out-a-gerrymander-in-a-pinch/

QGIS can do K-means clustering, but you should be aware of its pitfalls, for example it is likely to give you zones with widely varying population, if the population density is not fairly even:https://www.r-bloggers.com/2010/10/k-means-redistricting/ 
-Thayer


   On Thursday, April 22, 2021, 12:09:15 AM EDT, qgis-user-request at lists.osgeo.org <qgis-user-request at lists.osgeo.org> wrote:  > Date: Wed, 21 Apr 2021 16:29:57 -0500
> From: Jason Aleksi <jason.aleski at gmail.com>
> To: qgis-user at lists.osgeo.org
> Subject: [Qgis-user] Breaking a territory into zones
> Message-ID: <CALN462aKOBi6SgfqEgPHs=8HjVE+W5C=L5nCkTi0hg_jG4tMqQ at mail.gmail.com>> Content-Type: text/plain; charset="utf-8"
> 
> Can someone point me in the right direction?  I am not sure what I should
> be searching for in reference to the task below.
> 
> I work for a non-profit organization.  Up to this point, my limited GIS
> knowledge has been focused around plotting and integrating data with qGIS.
> I am tasked with finding a way to analyze the data and build "zones" within
> a territory based on the data with a street line center file.  I have
> searched for building zones, districts, territories, heatmaps, spatial
> statistics, voting districts, etc. I found some information relating to
> ESRI Business Analyst, but that was specific to ArcMap and did not point
> me in a related direction.
> 
> Here is the data I have:
> 
>   - Centerline File from the State GIS Office
>   - US Census Block Level data from 2010
>   - Various boundary files from the State GIS Office
> 
> What I am trying to do is break an territory up into 5 zones.  Each zone
> should have an equal number of residents.  Zone borders are limited to the
> edges of the territory.  Within the territory, zone borders should follow
> the nearest street centerline.
> 
> Can anyone offer a better direction, keywords to search for, or a feature I
> should look at within qGIS?
> 
> -JA-
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20210421/8feb5276/attachment-0001.html>
> 
> ------------------------------

  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20210423/2a32f48e/attachment.html>