<div dir="auto">Excuse me I HV been out for while and am far away from mapping issues kindly pliiz unsent these sms u keep send to me for yrs</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Aug 31, 2022, 10:00 PM <<a href="mailto:africa-request@lists.osgeo.org">africa-request@lists.osgeo.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Send Africa mailing list submissions to<br>
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Today's Topics:<br>
<br>
1. Re: Points Clustering/ Grouping - Seeking a Solution<br>
(Gavin Fleming)<br>
2. Re: Points Clustering/ Grouping - Seeking a Solution (E. Ndava)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Wed, 31 Aug 2022 07:07:55 +0200<br>
From: Gavin Fleming <<a href="mailto:gavinjfleming@gmail.com" target="_blank" rel="noreferrer">gavinjfleming@gmail.com</a>><br>
To: Africa local chapter discussions <<a href="mailto:africa@lists.osgeo.org" target="_blank" rel="noreferrer">africa@lists.osgeo.org</a>><br>
Subject: Re: [OSGeo Africa] Points Clustering/ Grouping - Seeking a<br>
Solution<br>
Message-ID: <<a href="mailto:90C8FE5F-9B6C-44C4-97BB-D375A08B2D4B@gmail.com" target="_blank" rel="noreferrer">90C8FE5F-9B6C-44C4-97BB-D375A08B2D4B@gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Hi Eric<br>
<br>
Nice to hear from you!<br>
<br>
also try DBSCAN <br>
<br>
k-means and DBSCAN are available natively in QGIS, PostGIS and GRASS, so also try these in the different implementations<br>
<br>
GRASS also has OPTICS and a couple of others (in v.cluster)<br>
<br>
I don?t think any method will give you the three pre-determined fixed number clusters it seems you are looking for. <br>
<br>
hth<br>
<br>
Gavin<br>
<br>
> On 31 Aug 2022, at 00:15, E. Ndava <<a href="mailto:erick.ndava@gmail.com" target="_blank" rel="noreferrer">erick.ndava@gmail.com</a>> wrote:<br>
> <br>
> Hello List Members,<br>
> <br>
> I have a set of 64 points I intend to group by proximity into three clusters (of 22, 22, 20) and am looking for a QGIS, PostGIS or any other OSS solution to this problem.<br>
> <br>
> I have Googled for one on the web and have skimmed <a href="https://gis.stackexchange.com/" rel="noreferrer noreferrer" target="_blank">https://gis.stackexchange.com/</a> <<a href="https://gis.stackexchange.com/" rel="noreferrer noreferrer" target="_blank">https://gis.stackexchange.com/</a>> and have not found an appropriate one (a.k.a ran out of patience).<br>
> <br>
> My starting point - Constrained K-Means Clustering, in QGIS did not yield acceptable results [ <a href="https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/" rel="noreferrer noreferrer" target="_blank">https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/</a> <<a href="https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/" rel="noreferrer noreferrer" target="_blank">https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/</a>> ] <br>
> <br>
> Looking forward to some pointers.<br>
> <br>
> Erick.<br>
> <br>
> PS:<br>
> List Inappropriate Content: (Ignore)<br>
> <br>
> The below clusters, Red, Green and Blue were produced by esri software (source under image)<br>
> <br>
> <group_analysis_attempt_2.PNG><br>
> <br>
> - I also tried the esri way (ArcGIS), Sort Tool which too did not produce acceptance (i.e. clusters not equally sized), results but something close. Source - [ <a href="https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293" rel="noreferrer noreferrer" target="_blank">https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293</a> <<a href="https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293" rel="noreferrer noreferrer" target="_blank">https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293</a>> ]<br>
> <br>
> - I do not have access to ArcPro.<br>
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<br>
Message: 2<br>
Date: Wed, 31 Aug 2022 08:23:54 +0200<br>
From: "E. Ndava" <<a href="mailto:erick.ndava@gmail.com" target="_blank" rel="noreferrer">erick.ndava@gmail.com</a>><br>
To: Africa local chapter discussions <<a href="mailto:africa@lists.osgeo.org" target="_blank" rel="noreferrer">africa@lists.osgeo.org</a>><br>
Subject: Re: [OSGeo Africa] Points Clustering/ Grouping - Seeking a<br>
Solution<br>
Message-ID:<br>
<CALcEFLy6teDAb+hKUh3+YeOK=<a href="mailto:4OY0YGenh6QSXTJoELgyJj-LQ@mail.gmail.com" target="_blank" rel="noreferrer">4OY0YGenh6QSXTJoELgyJj-LQ@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Hi Gavin.<br>
<br>
Great to hear from you too.<br>
<br>
Looks like it's a matter of trying several implementations, as you put it.<br>
No silver bullet.<br>
<br>
I will dig deeper on DBSCAN and give another go at k-means and brave it out<br>
with GRASS.<br>
<br>
<br>
*"I don?t think any method will give you the three pre-determined fixed<br>
number clusters it seems you are looking for."*<br>
Something close to start with is acceptable and can be modified with some<br>
manual intervention. My dataset is small and the desired clusters few. Now<br>
I see trouble brewing with a larger dataset, more clusters and weighted<br>
points.<br>
<br>
Thanks again<br>
<br>
On Wed, 31 Aug 2022 at 07:08, Gavin Fleming <<a href="mailto:gavinjfleming@gmail.com" target="_blank" rel="noreferrer">gavinjfleming@gmail.com</a>> wrote:<br>
<br>
> Hi Eric<br>
><br>
> Nice to hear from you!<br>
><br>
> also try DBSCAN<br>
><br>
> k-means and DBSCAN are available natively in QGIS, PostGIS and GRASS, so<br>
> also try these in the different implementations<br>
><br>
> GRASS also has OPTICS and a couple of others (in v.cluster)<br>
><br>
> I don?t think any method will give you the three pre-determined fixed<br>
> number clusters it seems you are looking for.<br>
><br>
> hth<br>
><br>
> Gavin<br>
><br>
> On 31 Aug 2022, at 00:15, E. Ndava <<a href="mailto:erick.ndava@gmail.com" target="_blank" rel="noreferrer">erick.ndava@gmail.com</a>> wrote:<br>
><br>
> Hello List Members,<br>
><br>
> I have a set of 64 points I intend to group by proximity into three<br>
> clusters (of 22, 22, 20) and am looking for a QGIS, PostGIS or any other<br>
> OSS solution to this problem.<br>
><br>
> I have Googled for one on the web and have skimmed<br>
> <a href="https://gis.stackexchange.com/" rel="noreferrer noreferrer" target="_blank">https://gis.stackexchange.com/</a> and have not found an appropriate one<br>
> (a.k.a ran out of patience).<br>
><br>
> My starting point - Constrained K-Means Clustering, in QGIS did not<br>
> yield acceptable results [<br>
> <a href="https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/" rel="noreferrer noreferrer" target="_blank">https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/</a> ]<br>
><br>
> Looking forward to some pointers.<br>
><br>
> Erick.<br>
><br>
> PS:<br>
> List Inappropriate Content: (Ignore)<br>
><br>
> The below clusters, Red, Green and Blue were produced by esri software<br>
> (source under image)<br>
><br>
> <group_analysis_attempt_2.PNG><br>
><br>
> - I also tried the esri way (ArcGIS), Sort Tool which too did not produce<br>
> acceptance (i.e. clusters not equally sized), results but something close.<br>
> Source - [<br>
> <a href="https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293" rel="noreferrer noreferrer" target="_blank">https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293</a><br>
> ]<br>
><br>
> - I do not have access to ArcPro.<br>
> _______________________________________________<br>
> Africa mailing list<br>
> <a href="mailto:Africa@lists.osgeo.org" target="_blank" rel="noreferrer">Africa@lists.osgeo.org</a><br>
> You can UNSUBSCRIBE at <a href="https://lists.osgeo.org/mailman/listinfo/africa" rel="noreferrer noreferrer" target="_blank">https://lists.osgeo.org/mailman/listinfo/africa</a><br>
><br>
><br>
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</blockquote></div>