I have a dataframe: sex age f 10 m 12 m 11 m 17 f 13 f 12 I 8 Want I want to calculate the mean of age per sex: f=> mean age = (10+13+12) /3 m=> mean age = (12+11+17) /3 I=> mean age = 8 I am trying something like this: combine(df,… Read More How to calculate mean of values per unique class