Summary functions and regular expressions

Hello, is it possible to use a regular expression within a summary function to return the mean of all the parameter values in the task that satisfy that expression? For example, I have a parameter called "ABC Density" in repeatable steps 1 and 2 of a recipe and I would like to calculate the mean of all the "ABC Density" values in both steps. I have tried to include a regular expression in the expression editor, but none have worked. Here is what I have tried so far:

summary("mean", select("^\d\.\d-ABC Density"))
select("...", where(match(parameter(...), "^\d\.\d-ABC Density")))

Any advice would be appreciated, thank you!