Graduated values in symbology based on specific attribute in QGIS

Question

I'm trying to solve the problem I've raised in Copying graduated scale from polygon to point layer in QGIS?

I've rearranged the attribute table that looks like this:

Important to notice is that the field "gruppo" is composed by 2 unique attributes: "campione" and "controllo".

What'd like to do now is to create a graduated symbology based on an attribute (say "pcb_101") and use the quantile classification.

BUT I need that each class of the quantile classification is based only of the "campione" rows of the "gruppo" field.

I tried to use the rule renderer but I noticed that, even if I add the rule "gruppo" = 'campione' and add intervals to this rule, the calculation of the quantiles is made using the whole "pcb_101" field.

Answer 1

Try

1. setting "gruppo" = 'campione' in General | Query.
2. Then do the classification.
3. Then remove the query again.

Hacky, but might work.