date appears to be a character variable, and R is treating it as such. str(dt1)
might give you some insight. Or the dplyr equivalent glimpse(dt1) I think R did what you asked, but if you want to be able to order records by date, in temporal order, you need to tell R that it is a date: library(dplyr) sums <- dt1 %>% mutate(realDate = as.Date(date, format = "%m/%d/%Y") %>% group_by(realDate) %>% summarise(EnergykWh = sum(EnergykWh)) --Chris Ryan roslinazairimah zakaria wrote: > Dear all, > > I have this set of data. I would like to sum the EnergykWh according date > sequences. > >> head(dt1,20) StationName date time EnergykWh > 1 PALO ALTO CA / CAMBRIDGE #1 1/14/2016 12:09 4.680496 > 2 PALO ALTO CA / CAMBRIDGE #1 1/14/2016 19:50 6.272414 > 3 PALO ALTO CA / CAMBRIDGE #1 1/14/2016 20:22 1.032782 > 4 PALO ALTO CA / CAMBRIDGE #1 1/15/2016 8:25 11.004884 > 5 PALO ALTO CA / CAMBRIDGE #1 1/15/2016 14:23 10.096824 > 6 PALO ALTO CA / CAMBRIDGE #1 1/15/2016 18:17 6.658797 > 7 PALO ALTO CA / CAMBRIDGE #1 1/15/2016 21:46 4.808874 > 8 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 10:19 1.469384 > 9 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 12:12 2.996239 > 10 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 14:12 0.303222 > 11 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 16:22 4.988339 > 12 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 19:16 8.131804 > 13 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 19:19 0.117156 > 14 PALO ALTO CA / CAMBRIDGE #1 1/16/2016 20:24 3.285669 > 15 PALO ALTO CA / CAMBRIDGE #1 1/17/2016 9:54 1.175608 > 16 PALO ALTO CA / CAMBRIDGE #1 1/17/2016 12:16 3.677487 > 17 PALO ALTO CA / CAMBRIDGE #1 1/17/2016 13:53 1.068393 > 18 PALO ALTO CA / CAMBRIDGE #1 1/17/2016 19:03 8.820755 > 19 PALO ALTO CA / CAMBRIDGE #1 1/17/2016 22:00 8.138583 > 20 PALO ALTO CA / CAMBRIDGE #1 1/18/2016 8:58 9.057500 > > I have tried this: > library(dplyr) > sums <- dt1 %>% > group_by(date) %>% > summarise(EnergykWh = sum(EnergykWh)) > > head(sums,20) > > The date is not by daily sequence but by year sequence. > >> head(sums,20)# A tibble: 20 × 2 > date EnergykWh > <chr> <dbl> 1 1/1/2017 25.3 2 1/1/2018 61.0 3 > 1/1/2019 0.627 4 1/1/2020 10.7 5 1/10/2017 69.4 6 > 1/10/2018 54.5 7 1/10/2019 49.1 8 1/10/2020 45.9 9 > 1/11/2017 73.9 10 1/11/2018 53.3 11 1/11/2019 93.5 12 > 1/11/2020 66.7 13 1/12/2017 78.6 14 1/12/2018 42.2 15 > 1/12/2019 22.7 16 1/12/2020 80.9 17 1/13/2017 85.6 18 > 1/13/2018 46.4 19 1/13/2019 40.0 20 1/13/2020 121. > > > > Thank you very much for any help given. > > ______________________________________________ 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.