[R] Problem with GMT+/- time zones

[Andrew Digby]

I'm struggling with time zone version when expressed as hours offset from GMT. Can anyone confirm that the behaviour below is incorrect? It seems that the GMT offsets are backwards:

> format(as.POSIXct("2011-05-23 17:23:00", tz="Europe/London"),tz="America/New_York",usetz=T)
[1] "2011-05-23 12:23:00 EDT"

- this works.

> format(as.POSIXct("2011-05-23 17:23:00",tz="GMT"),tz="GMT-5",usetz=T)
[1] "2011-05-23 22:23:00 GMT"

- this doesn't work: 17:23:00 GMT should be 12:23:00 GMT-5!


Thanks.


R version 2.13.0 (2011-04-13)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)