计算几个数据集的每日，每月和每年平均值

I have a data frame:

我有一个数据框:

MS_NR SS_NR      DATE       HOUR     VALUE
1 13095010    68 1/01/2014 0:00:00    9,8
2 13095010    68 1/01/2014 1:00:00    8,0
3 13095010    68 1/01/2014 2:00:00    NA
4 13095010    68 1/01/2014 3:00:00    7,5
5 13095010    68 1/01/2014 4:00:00    7,0
6 13095010    68 1/01/2014 5:00:00    8,5
MS_NR SS_NR