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I have data on two characteristics for a particular variable, say volume and quality. I want to plot these using proportional symbol map in QGIS. For Volume, I could plot using: Symbology -> Graduated -> value (Volume) + Method (Size).

But if I want to show the quality by colour, say the best quality in green, medium in yellow and bad quality in red. How to plot a bivariate map in QGIS?

For example, I have following data:

enter image description here

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  • How about adding labels? Can you provide some exemplary data?
    – Erik
    Jun 2, 2021 at 10:13
  • I tried to copy paste the data, but I came out as an image.
    – rgt
    Jun 2, 2021 at 10:28

2 Answers 2

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It is also possible to work with a "Quality" field directly, without creation of additional field

result

For Graduated symbology values from the field "Value 1" were used.


References:

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  • This seems easier as earlier I was using 'Categorized' for plotting volume. However, since I created the numeric quality field, I used that field only for colour coding. But, by default, it was getting colours for 1.5, 2.5. Can I customize it to show colors only for 1,2 & 3?
    – rgt
    Jun 2, 2021 at 11:07
  • To me it sounds like a new question on GIS SE
    – Taras
    Jun 2, 2021 at 11:25
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First, code your Quality attribute in numerical form, using field calculator, creating a new field q1:

case 
when quality = 'low' then 1
when quality = 'medium' then 2
when quality = 'high' then 3
end

Than use this field with data driven override / assistant to set the color based on this field:

Defining the settings in the assistant: enter image description here

Layer styling panel:Data driven override / Opening the assistant:

enter image description here

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  • Thanks for the solution. I got the first step. Can you elaborate second part?
    – rgt
    Jun 2, 2021 at 10:37
  • I added an additional screenshot: does that help?
    – Babel
    Jun 2, 2021 at 10:42

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