Calculate percentage of vector point attributes within a polygon QGIS

Question

I have a vector point layer with an attribute Customer with boolean values true and false. I want to aggregate this data by polygons, such that for a given polygon, it shows that Customer is XX% true and YY% false. I can't achieve this with join attributes by location (summary); I can only get Customer_COUNT from this.

Attached an example for reference -- I basically want to get the % blue and green points within a polygon.

Answer 1

You can use field calculator with overlay_contains() (or eventually overlay_intersects() depending on your needs) expression on your polygons for this. To get the count for each category simply set a filter to your needs, for example:

array_length(overlay_contains('points',$id,filter:="cat"=0))

respectively for the other category

array_length(overlay_contains('points',$id,filter:="cat"=1))

Then calculate the percentage from these. So all in one:

array_length(overlay_contains('points',$id,filter:="cat"=1))
/
array_length(overlay_contains('points',$id))

Just replace points with the name of your points layer and "cat"=1 with your field containing the category and the desired value of this category.

Answer 2

Try this expression in the polygon layer:

with_variable(
    'values',
    overlay_contains('point layer name/id', "Customer"), -- replace here with your values
    with_variable(
        'total',
        100 / array_length(@values),
        format(
            '%1% true, %2% false', -- output will look like ##% true, ##% false.
            @total * array_count(@values, true), -- quote true if your field in the point layer is not boolean or is string
            @total * array_count(@values, false) -- same as above
        )
    )
)

you can control the format of the result modifying this line ('%1% true, %2% false') as explained here, for example: 'true: %1%, false: %2%' will look like true: ##%, false: ##%.

Answer 3

You can use "Count Features in Features by Category" from ProcessX Plug-In for this usecase.

Choose your polygons as Source-Layer, your points as Overlay-Layer, add the field containing your Customer as Category-Expression. As desired output structure I assume you want to choose Create a field for each category. Adjust the other settings if needed as well.

This will produce a copy of your polygon layer with two new fields added: Customer_True and Customer_False. Then use field calculator to calculate the percentage out of these.

Disclaimer: I am the author of that Plug-In.