lubridate
makes it easier to work with dates and time. library(lubridate); for (sec in seq(36300, 92000, by=7*60)) { sec_p <- seconds_to_period(sec); hr_mi <- sprintf('%02d:%02d', sec_p@hour, minute(sec_p)); print(hr_mi); }
library(lubridate) dt_1 <- ymd('20170213') dt_2 <- mdy('09282016') dt_3 <- dmy('22032017') dt_1 # [1] "2017-02-13 UTC" dt_2 # [1] "2016-09-28 UTC" dt_3 # [1] "2017-03-22 UTC"