R: date formatting ignores timezone for POSIXlt objects

Asked Dec 09 '15 at 13:03

Active Dec 09 '15 at 15:28

Viewed 88 times

I cannot get R to format POSIXlt objects in the desired timezone. POSIXct works as expected. Is this a bug or am I missing something?

date.str = "2015-12-09 13:30"
from = "Europe/London"
to = "America/Los_Angeles"

lt = as.POSIXlt(date.str, tz=from)
format(lt, tz=to, usetz=TRUE)
#[1] "2015-12-09 13:30:00 GMT"

ct = as.POSIXct(date.str, tz=from)
format(ct, tz=to, usetz=TRUE)
#[1] "2015-12-09 05:30:00 PST"

The tzone attributes are the same:

attributes(ct)$tzone
#[1] "Europe/London"
attributes(lt)$tzone
#[1] "Europe/London"

Solution

As pointed out by @nicola, format.POSIXlt has no tz parameter. To print a POSIXlt date in another timezone one can use lubridate package to convert a POSIXlt object to the desired timezone first:

require(lubridate)
lt.changed = with_tz(lt, tz=to)
format(lt.changed, usetz=TRUE)
#[1] "2015-12-09 05:30:00 PST"

edited Dec 09 '15 at 15:28

asked Dec 09 '15 at 13:03

Ilya Kolpakov

1

Slightly confused with what you are trying to achieve. Your output is correct `13:30 GTM` is `05:30 PST` and `ct == lt` in your example hence why the `tzone` attributes are the same. What is it you are trying to do? – amwill04 Dec 09 '15 at 13:25
1

See `formalArgs(format.POSIXct)` and `formalArgs(format.POSIXlt)`: the `tz` argument doesn't exist for `POSIXlt` objects. – nicola Dec 09 '15 at 13:28
@amwill04, I want to print time in a certain zone as UTC time. – Ilya Kolpakov Dec 09 '15 at 15:20
@nicola, nice trick, thanks! – Ilya Kolpakov Dec 09 '15 at 15:36
1

There's no need for lubridate here at all - just `format(as.POSIXct(lt), tz=to, usetz=TRUE)` and you're done. – thelatemail Dec 14 '15 at 01:28

R: date formatting ignores timezone for POSIXlt objects

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