How to change the color ramp of a rule based styling in QGIS?

Question

I use rule-based styling in QGIS, in order to do spatial quantile, computed in R. If I want to change the color ramp, I need to either: change every class color, or set graduated then change the color ramp and go back to rule-based and re-enter my classes thresholds.

Is there a way to change the color ramp for a rule-based styling directly into the rule-based panel ?

Answer 1

You can define the filling of a single symbol as a color ramp, defined by data values.

Edit your symbology, click the drop-down list data defined override (on the right of the color menu) and click on "edit" to define a color by expression, for exemple:

CASE 
WHEN "attribute" < 0 THEN 'red'
WHEN "attribute" > 100 THEN 'blue'
ELSE 'yellow'
END

You can also use the assistant in the same drop-down menu to define your threshold with an attribute or an expression and the value ramp associated. This will define the color with a color-ramp expression like this:

coalesce(ramp_color('custom ramp',scale_linear("attribute", 0, 9, 0, 1)), '#000000')