I don't have a quick answer for you, but I've found this resource very helpful for many such problems in R:

https://discdown.org/rprogramming/classes-and-methods.html#classes-and-methods-date-and-datetime

Hopefully you find it useful!

Hi Hasan,

dates are internally saved as the number of days from a certain start date (called 'origin' in R, standard origin is 1970-01-01). For example, the following code:

as.numeric(as.Date("2022-01-25"))

yields 19017, meaning that '2022-01-25' is 19017 days after 1970-01-01.

The numbers you mentioned (e.g. 1836518400) are numeric representations of datetime-objects (including hours, minutes and seconds) and indicate the number of seconds (rather than days) after 1970-01-01 00:00:00. So if you want to convert the numbers to a date object, you have to first convert it to POSIXct:

as.Date(as.POSIXct(1836518400, origin = "1970-01-01 00:00:00"))

Depending on where you got your data from, the origin might differ from 1970 (e.g. excel uses different origins). Just try with a few of your numbers and see whether the dates you get are reasonable.

Hasan Bin Sohail

To convert character data to dates, use the as. Date() method. Date(x, "format"), where x is the character data and format returns the proper format.

Furthermore, see https://stackoverflow.com/questions/38146160/how-to-convert-dd-mm-yy-to-yyyy-mm-dd-in-r