Примените разницу и среднее значение между группами в столбце R

#r #dplyr #tidyr Вопрос: У меня есть фрейм данных, такой : df = data.frame("subjectID" = c("S1","S2","S2","S1","S1","S2","S2","S1","S1","S2","S1","S2"), "treatment" = c("none","none","none","none","drug1","drug1","drug1","drug1","drug2","drug2","drug2","drug2"), "protein" = c("proteinA","proteinA","proteinB","proteinB","proteinA","proteinA","proteinB","proteinB","proteinA","proteinA","proteinB","proteinB"), "value"= c(5.3,4.3,4.5,2.3,6.5,5.4,1.2,3.2,2.3,4.5,6.5,3.4)) subjectID treatment protein value 1 S1…