[OSGeo Africa] Africa Digest, Vol 184, Issue 11

Wed Aug 31 12:05:06 PDT 2022

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

On Wed, Aug 31, 2022, 10:00 PM <africa-request at lists.osgeo.org> wrote:

> Send Africa mailing list submissions to
>         africa at lists.osgeo.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://lists.osgeo.org/mailman/listinfo/africa
> or, via email, send a message with subject or body 'help' to
>         africa-request at lists.osgeo.org
>
> You can reach the person managing the list at
>         africa-owner at lists.osgeo.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Africa digest..."
>
>
> Today's Topics:
>
>    1. Re: Points Clustering/ Grouping - Seeking a Solution
>       (Gavin Fleming)
>    2. Re: Points Clustering/ Grouping - Seeking a Solution (E. Ndava)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 31 Aug 2022 07:07:55 +0200
> From: Gavin Fleming <gavinjfleming at gmail.com>
> To: Africa local chapter discussions <africa at lists.osgeo.org>
> Subject: Re: [OSGeo Africa] Points Clustering/ Grouping - Seeking a
>         Solution
> Message-ID: <90C8FE5F-9B6C-44C4-97BB-D375A08B2D4B at gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Eric
>
> Nice to hear from you!
>
> also try DBSCAN
>
> k-means and DBSCAN are available natively in QGIS, PostGIS and GRASS, so
> also try these in the different implementations
>
> GRASS also has OPTICS and a couple of others (in v.cluster)
>
> I don?t think any method will give you the three pre-determined fixed
> number clusters it seems you are looking for.
>
> hth
>
> Gavin
>
> > On 31 Aug 2022, at 00:15, E. Ndava <erick.ndava at gmail.com> wrote:
> >
> > Hello List Members,
> >
> > 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.
> >
> > I have Googled for one on the web and have skimmed
> https://gis.stackexchange.com/ <https://gis.stackexchange.com/> and have
> not found an appropriate one (a.k.a ran out of patience).
> >
> > My starting point - Constrained K-Means Clustering, in QGIS did not
> yield acceptable results [
> https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/ <
> https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/> ]
> >
> > Looking forward to some pointers.
> >
> > Erick.
> >
> > PS:
> > List Inappropriate Content:  (Ignore)
> >
> > The below clusters, Red, Green and Blue were produced by esri software
> (source under image)
> >
> > <group_analysis_attempt_2.PNG>
> >
> > - 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 - [
> https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293
> <
> https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293>
> ]
> >
> > - I do not have access to ArcPro.
> > _______________________________________________
> > Africa mailing list
> > Africa at lists.osgeo.org
> > You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://lists.osgeo.org/pipermail/africa/attachments/20220831/6451fea5/attachment-0001.htm
> >
>
> ------------------------------
>
> Message: 2
> Date: Wed, 31 Aug 2022 08:23:54 +0200
> From: "E. Ndava" <erick.ndava at gmail.com>
> To: Africa local chapter discussions <africa at lists.osgeo.org>
> Subject: Re: [OSGeo Africa] Points Clustering/ Grouping - Seeking a
>         Solution
> Message-ID:
>         <CALcEFLy6teDAb+hKUh3+YeOK=
> 4OY0YGenh6QSXTJoELgyJj-LQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Gavin.
>
> Great to hear from you too.
>
> Looks like it's a matter of trying several implementations, as you put it.
> No silver bullet.
>
> I will dig deeper on DBSCAN and give another go at k-means and brave it out
> with GRASS.
>
>
> *"I don?t think any method will give you the three pre-determined fixed
> number clusters it seems you are looking for."*
> Something close to start with is acceptable and can be modified with some
> manual intervention. My dataset is small and the desired clusters few. Now
> I see trouble brewing with a larger dataset, more clusters and weighted
> points.
>
> Thanks again
>
> On Wed, 31 Aug 2022 at 07:08, Gavin Fleming <gavinjfleming at gmail.com>
> wrote:
>
> > Hi Eric
> >
> > Nice to hear from you!
> >
> > also try DBSCAN
> >
> > k-means and DBSCAN are available natively in QGIS, PostGIS and GRASS, so
> > also try these in the different implementations
> >
> > GRASS also has OPTICS and a couple of others (in v.cluster)
> >
> > I don?t think any method will give you the three pre-determined fixed
> > number clusters it seems you are looking for.
> >
> > hth
> >
> > Gavin
> >
> > On 31 Aug 2022, at 00:15, E. Ndava <erick.ndava at gmail.com> wrote:
> >
> > Hello List Members,
> >
> > 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.
> >
> > I have Googled for one on the web and have skimmed
> > https://gis.stackexchange.com/ and have not found an appropriate one
> > (a.k.a ran out of patience).
> >
> > My starting point - Constrained K-Means Clustering, in QGIS did not
> > yield acceptable results [
> > https://spatialthoughts.com/2021/01/31/equal-sized-kmeans-qgis/ ]
> >
> > Looking forward to some pointers.
> >
> > Erick.
> >
> > PS:
> > List Inappropriate Content:  (Ignore)
> >
> > The below clusters, Red, Green and Blue were produced by esri software
> > (source under image)
> >
> > <group_analysis_attempt_2.PNG>
> >
> > - 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 - [
> >
> https://community.esri.com/t5/spatial-data-science-questions/group-every-near-50-points-together/m-p/167184?commentID=687372#comment-687293
> >  ]
> >
> > - I do not have access to ArcPro.
> > _______________________________________________
> > Africa mailing list
> > Africa at lists.osgeo.org
> > You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
> >
> >
> > _______________________________________________
> > Africa mailing list
> > Africa at lists.osgeo.org
> > You can UNSUBSCRIBE at https://lists.osgeo.org/mailman/listinfo/africa
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://lists.osgeo.org/pipermail/africa/attachments/20220831/a63a1203/attachment-0001.htm
> >
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Africa mailing list
> Africa at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/africa
>
>
> ------------------------------
>
> End of Africa Digest, Vol 184, Issue 11
> ***************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20220831/e21fe3f0/attachment.htm>