万人往LVR 发表于 2016-3-20 21:33 
> tapply(dataamount,datatime,sum)
Error in tapply(dataamount, datatime, sum) : 找不到对象'datatime'
> tapply(data$amount,data$time,sum)
Error in Summary.factor(c(1L, 36L, 253L, 110L, 1L, 142L, 1L, 92L, 199L, :
‘sum’ not meaningful for factors
您好,出错了。请问错误在哪里啊?我是要将相同日期的Amount数据加总起来。