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.