我是R的新手data.table,我发现它很有用而且很快.我正在尝试加入2个数据表:
> TotFreq
Legacy_Store_Number WeekDay Date Item_Key Distr NoSellingDays meanUnits ItemType
1: 113802 1 2013-03-24 000000000120 2.428985e-04 0 8.00 FM
2: 113802 1 2013-03-24 000000000126 1.104030e-03 0 47.50 FM
3: 113802 1 2013-03-24 000000000170 1.126004e-03 0 48.75 FM
4: 113802 1 2013-03-24 000000000180 5.143034e-04 0 19.00 FM
5: 113802 1 2013-03-24 000000000260 3.854306e-04 0 12.25 FM
160167: 113802 7 2013-03-23 978125002327 5.902655e-07 27 1.00 SM
160168: 113802 7 2013-03-23 978141970584 1.770796e-06 25 1.00 SM
160169: 113802 7 2013-03-23 …