R中“ ifelse”语句内的“聚合”函数

Question

I am trying to used "aggregate" function inside of "ifelse" statement in R. I want to return NA if min sale is equal to 0 then if not aggregate it. like the codes below:

 df <- data.frame(day=c("Mon","Tue","Mon","Tue","Tue","Tue"),sales=c(799,1359,1359,1359,1359,1359))
df2 <- ifelse(min(df$sales)==0,NA,aggregate(sales~day,data=df,sum))

My problem is that it return this:

[[1]]
[1] Mon Tue
Levels: Mon Tue

I want it to to return a data frame like usually aggregate:

 day sales
1 Mon  2158
2 Tue  5436

Answer 1

除了@ A.Webb的注释，我想您还想使用匿名函数将if内部aggregate放入：

aggregate(sales ~ day, data=df, function(x) if(min(x)==0) NA else sum(x) )