Calculate the mean by group

Question

I have a large data frame that looks similar to this:

df <- data.frame(dive = factor(sample(c("dive1","dive2"), 10, replace=TRUE)),
            


        

Answer 1

aggregate(speed~dive,data=df,FUN=mean)
   dive     speed
1 dive1 0.7059729
2 dive2 0.5473777