Be careful with the time zone
> example = as.POSIXct(“1957-09-30 16:00:00”)
> example
[1] “1957-09-30 16:00:00 PST”
> as.Date(example)
[1] “1957-10-01”
> as.Date(example, tz = Sys.timezone())
[1] “1957-09-30”
The problem is that as.POSIXct() uses system timezone as default time zone and as.Date() uses UTC as default timezone.
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