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<div dir="ltr" data-setdir="false">Hi Jason,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">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.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">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.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">This is a recent blog post about using R for computational redistricting:</div><div dir="ltr" data-setdir="false"><a href="https://www.r-bloggers.com/2021/02/some-computational-redistricting-methods-or-how-to-sniff-out-a-gerrymander-in-a-pinch/" rel="nofollow" target="_blank">https://www.r-bloggers.com/2021/02/some-computational-redistricting-methods-or-how-to-sniff-out-a-gerrymander-in-a-pinch/</a><br></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">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:</div><div dir="ltr" data-setdir="false"><a href="https://www.r-bloggers.com/2010/10/k-means-redistricting/" rel="nofollow" target="_blank">https://www.r-bloggers.com/2010/10/k-means-redistricting/</a> </div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">-Thayer</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"><br></div><div><br></div>
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<div>On Thursday, April 22, 2021, 12:09:15 AM EDT, qgis-user-request@lists.osgeo.org <qgis-user-request@lists.osgeo.org> wrote:
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<div>> Date: Wed, 21 Apr 2021 16:29:57 -0500<br></div><div><div dir="ltr">> From: Jason Aleksi <<a href="mailto:jason.aleski@gmail.com" rel="nofollow" target="_blank">jason.aleski@gmail.com</a>><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>To: <a href="mailto:qgis-user@lists.osgeo.org" rel="nofollow" target="_blank">qgis-user@lists.osgeo.org</a><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Subject: [Qgis-user] Breaking a territory into zones<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Message-ID: <CALN462aKOBi6SgfqEgPHs=8HjVE+W5C=<a href="mailto:L5nCkTi0hg_jG4tMqQ@mail.gmail.com" rel="nofollow" target="_blank">L5nCkTi0hg_jG4tMqQ@mail.gmail.com</a>></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Content-Type: text/plain; charset="utf-8"<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Can someone point me in the right direction? I am not sure what I should<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>be searching for in reference to the task below.<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>I work for a non-profit organization. Up to this point, my limited GIS<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>knowledge has been focused around plotting and integrating data with qGIS.<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>I am tasked with finding a way to analyze the data and build "zones" within<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>a territory based on the data with a street line center file. I have<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>searched for building zones, districts, territories, heatmaps, spatial<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>statistics, voting districts, etc. I found some information relating to<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>ESRI Business Analyst, but that was specific to ArcMap and did not point<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>me in a related direction.<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Here is the data I have:<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span> - Centerline File from the State GIS Office<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span> - US Census Block Level data from 2010<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span> - Various boundary files from the State GIS Office<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>What I am trying to do is break an territory up into 5 zones. Each zone<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>should have an equal number of residents. Zone borders are limited to the<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>edges of the territory. Within the territory, zone borders should follow<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>the nearest street centerline.<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>Can anyone offer a better direction, keywords to search for, or a feature I<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>should look at within qGIS?<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>-JA-<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>-------------- next part --------------<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>An HTML attachment was scrubbed...<br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>URL: <<a href="http://lists.osgeo.org/pipermail/qgis-user/attachments/20210421/8feb5276/attachment-0001.html" rel="nofollow" target="_blank">http://lists.osgeo.org/pipermail/qgis-user/attachments/20210421/8feb5276/attachment-0001.html</a>><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span><br></div><div dir="ltr" data-setdir="false"><span><span style="color: rgb(38, 40, 42); font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">> </span></span>------------------------------<br></div><div dir="ltr"><br></div></div>
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