Unexpected date when converting POSIXct date-time to Date - can timezone fix it?

Question

When I try to coerce a POSIXct date-time to a Date using as.Date, it seems to return wrong date.

I suspect it has got something to

Answer 1

The clue is in the warning message. as.Date() doesn't know how to interpret IST as a timezone and so defaults to UTC. Assuming that IST is Indian Standard Time (rather than Irish Standard time) and that IST is UTC+5:30, as.Date() is giving the expected result, even if it is incorrect for your purposes.

Providing a date with a timezone expressed as an offset from UTC gives the desired result.

as.Date("2020-03-24 00:02:00 UTC+5:30")
[1] "2020-03-24"