Getting mean and standard deviation from groups in a data.frame

Question

I have heart rate data in the form of a list with the four categories 1AS, 1CS, 1AI, 1CI each of variable size. I would like to output mean and standard deviations for each

Answer 1

Another solution using ave:

ave(DF$HR, DF$Group)

gives the mean and

ave(DF$HR, DF$Group, FUN=sd)

with DF being your data frame.