Hi there, I am trying to get the sum of rain per day.
That is what the data-set looks like: Timestamp Rain_mm_Tot 2017-05-29 23:40:00 4.7999980 2017-05-29 23:50:00 1.2000000 2017-05-30 00:10:00 2.5800000 2017-05-30 00:20:00 1.2009600 2017-05-30 00:30:00 1.2000006 2017-05-30 00:40:00 2.5002480 First I tried to define the column as date format with: data_date <-data[as.Date(data_date$Timestamp)<=as.Date("2017-06-15"),] Then I tried to aggregate as followed: data_date_sum <- aggregate(data_date$Timestamp, on = "days", k=1, by=list(cut(as.Date(data_date$Date))), FUN=sum) R responds: Error in as.Date.default(data_date$Date) : do not know how to convert 'data_date$Date' to class “Date” I read serveral post, but no other fits to my format. Because I am a beginner I am open for completely new ideas to sum the daily rain also. Thanks a lot and all the best Torben [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.