[Qgis-user] Draw Ellipse/Polygons for areas of maximum concentration

[Nyall Dawson]

On Fri, 30 Apr 2021 at 15:01, chris hermansen <clhermansen at gmail.com> wrote:
>
> Krishna and list,
>
> On Thu, Apr 29, 2021 at 7:45 PM chris hermansen <clhermansen at gmail.com> wrote:
>>
>> Krishna and list
>>
>> On Thu, Apr 29, 2021, 15:24 krishna Ayyala <ayyalakrishna at gmail.com> wrote:
>>>
>>> Chris,
>>> Thanks for the reply. Yes, I did run k-means clustering for 4 clusters. It is creating a new layer called "clusters". This layer has a field called Cluster_id, ranging from 1 to 4. But, this method is considering all the points within the circle. I am looking for the points outside the ellipses to be omitted (should not be considered). Also K-means clustering is not generating any polygons/ellipses. We have to identify a cluster based on the Cluster_ID. I am curious if there is any tool within Qgis that can produce results similar to the circle with ellipses?
>>
>>
>> If you symbolize your points by colour according to the cluster_id does the clustering look acceptable to you?
>>
>>>
>
> Thinking about your diagram, maybe you want to fit ellipses to point clusters.  If that's the case, maybe this paper is of some help:
>
> https://www.researchgate.net/publication/276433770_Multiple_ellipse_fitting_by_center-based_clustering/fulltext/56293cc208aef25a243d5d3a/Multiple-ellipse-fitting-by-center-based-clustering.pdf


You could try this plugin : https://plugins.qgis.org/plugins/SDEllipse/

Nyall



>
> I imagine you'd need to program this yourself.
>
>
> --
> Chris Hermansen · clhermansen "at" gmail "dot" com
>
> C'est ma façon de parler.
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