我有这个代码:
dat<-dat[,list(colA,colB
,RelativeIncome=Income/.SD[Nation=="America",Income]
,RelativeIncomeLog2=log2(Income)-log2(.SD[Nation=="America",Income])) #Read 1)
,by=list(Name,Nation)]
1)我想说"RelativeIncomeLog2=log2(RelativeIncome)",但是 "RelativeIncome"在j范围内是不可用的？
2)我尝试了以下代码(根据data.table FAQ).现在"RelativeIncome"可用,但它不添加列:
dat<-dat[,{colA;colB;RelativeIncome=Income/.SD[Nation=="America",Income];
,RelativeIncomeLog2=log2(RelativeIncome)]))
,by=list(Name,Nation)]