Compute daily, month and annual average of several data sets
问题 I have a data frame: 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 are temperature observations of a weather station taken every hour, I want to calculate the daily, weekly, monthly and annual averages of several data frames of different weather stations. How can I do this within a loop, so that the