aggregate(汇总数据~分类项,data=df ,FUN="sum")
示例:aggregate(weight ~ feed, data = chickwts, mean)aggregate(breaks ~ wool + tension, data = warpbreaks, mean)aggregate(cbind(Ozone, Temp) ~ Month, data = airquality, mean)aggregate(cbind(ncases, ncontrols) ~ alcgp + tobgp, data = esoph, sum)