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I have a question about the quantile classification in QGIS (2.6 and master, windows or linux).

I used the points in polygon fonction. I have 100 polygons.

In the attributes of my 100 polygon I get the number of points for each polygon.

How can I reclassify this layer into ten classes of equal numbers of points?

If I use the quantile classification, QGIS divide the number of polygon in ten and colour each of them in a colour. It does not take into account of the numbers of points in each polygon.

My goal is to measure the grouping of points and to be able to say, this 3 polygons group 10 % of the total size.

these 10 polygons group 50 % of the totale size ...etc

Is there a method to to this whith QGIS ?

  • The coloring does take into account the number of points, assuming you set it to the attribute column you created during the point-in-polygon operation. But what you're describing is really a kind of clustering operation. I don't think there's an off-the-shelf way to do this, I think it will require writing code in Python or another language that can handle spatial data. And the solution won't be unique. Please clarify if I don't understand your requirements. – Lee Hachadoorian Nov 5 '14 at 1:37
  • Yes of course, i set the coloring to the PNTCNT column. The goal of this operation is to vizualise how points concentrate into the space. – Cyrille Nov 5 '14 at 9:03
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This may not apply to your situation as it may depend on the attributes of the points but I have a point layer where I use their unique ID attribute and created 10 classes of equal count (quantile):

Style

Result

You can create unique attributes if you don't already have one by using the Field Calculator and adding $rownum in the expression. Hope this helps.

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