Aggregating a dataframe dynamically with column names in strings from another dataframe

Question

Ok, so I have a configuration dataframe that will specify, how I want to aggregate a few columns in another dataframe.

config frame:

conf <- rbind(            


        

Answer 1

Stealing @Justin's suggestion here's what I ended up doing.

aggregate(as.formula(paste("cnt", 
                           paste(conf[,1], collapse=" + "), 
                           sep=" ~ ")), data=dd, sum)