R help - Nov 2015 - Converting time zones in R using metadata file information of video files, help needed.

Hi,

I have video files (FAT) that are taken in a different timezone than my
current location. The modification date/time in the metafila data of the
video file shows the time video was taken, although in the current timezone
of my computer, if I understand right.

I wish to convert the date/time to the origin. The video was taken in
London, Ontario Canada at 2015-06-21 07:53:28, when looking at the metadata
of the file on my computer (timezone "Europe/Berlin") it says
modification
date "2015-06-22 01:53:28". Hence, there is a 6 hour difference
between the
two time-zones

I use the script provided here:
http://blog.revolutionanalytics.com/2009/06/converting-time-zones.html

pb.txt <- "2015-06-22 01:53:28" #modification date as shown on my
computer (timezone
"Europe/Berlin")

pb.date <- as.POSIXct(pb.txt, tz="Europe/London")

pb.date <- as.POSIXct(pb.txt, tz="America/Toronto")#timezone of
origin
video camera location

format(pb.date, tz=local.time,usetz=TRUE) #formats the mtime to data and
time when the video was taken

[1] "2015-06-22 07:53:28 CEST" # the time is correct but the date is
wrong
as it has added 6 hours rather than subtracting.

I find working with different time-zones to be difficult, I hope I managed
to formulate an understandable question.

Regards,

Kes

	[[alternative HTML version deleted]]

> On Nov 22, 2015, at 2:52 AM, Ronny Steen <kestrel1978 at gmail.com>
wrote:
> 
> Hi,
> 
> I have video files (FAT) that are taken in a different timezone than my
> current location. The modification date/time in the metafila data of the
> video file shows the time video was taken, although in the current timezone
> of my computer, if I understand right.
> 
> I wish to convert the date/time to the origin. The video was taken in
> London, Ontario Canada at 2015-06-21 07:53:28, when looking at the metadata
> of the file on my computer (timezone "Europe/Berlin") it says
modification
> date "2015-06-22 01:53:28". Hence, there is a 6 hour difference
between the
> two time-zones
> 
> I use the script provided here:
> http://blog.revolutionanalytics.com/2009/06/converting-time-zones.html
> 
> pb.txt <- "2015-06-22 01:53:28" #modification date as shown on
my
> computer (timezone
> "Europe/Berlin")
> 
> pb.date <- as.POSIXct(pb.txt, tz="Europe/London")
> 
> pb.date <- as.POSIXct(pb.txt, tz="America/Toronto")#timezone
of origin
> video camera location
> 
> format(pb.date, tz=local.time,usetz=TRUE) #formats the mtime to data and
> time when the video was taken
> 
> [1] "2015-06-22 07:53:28 CEST" # the time is correct but the date
is wrong
> as it has added 6 hours rather than subtracting.
I don?t understand why that is not the correct calculation, since the Sun rises
in the East and so the local time is ?later? in Berlin than in Toronto. When it
is later in the day in a more Westerly TZ the calculations on dates are
correct>
> pb.txt <- "2015-06-22 21:53:28"
> pb.date <- as.POSIXct(pb.txt)
> pb.date
[1] "2015-06-22 21:53:28 PDT"
> format( pb.date, tz="Europe/Berlin")
[1] "2015-06-23 06:53:28"
> 
> I find working with different time-zones to be difficult, I hope I managed
> to formulate an understandable question.
With R the timezomes are mainly useful for output (including `print`-ing results
in the current locale) and the options on input are limited. The numeric value
is always in GMT/UCT.

> 
> Regards,
> 
> Kes
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA

The "lubridate" package will help simplify these time zone
conversions. It provides two simple functions with_tz and force_tz that
conceptually make things simpler.

library(lubridate)
> x <- as.POSIXct("2015-06-22 01:53:28",
'Europe/Berlin')
> with_tz(x, 'America/Toronto')
[1] "2015-06-21 19:53:28 EDT"

HTH,

J

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ronny Steen
Sent: Sunday, November 22, 2015 2:52 AM
To: r-help at r-project.org
Subject: [R] Converting time zones in R using metadata file information of video
files, help needed.

Hi,

I have video files (FAT) that are taken in a different timezone than my current
location. The modification date/time in the metafila data of the video file
shows the time video was taken, although in the current timezone of my computer,
if I understand right.

I wish to convert the date/time to the origin. The video was taken in London,
Ontario Canada at 2015-06-21 07:53:28, when looking at the metadata of the file
on my computer (timezone "Europe/Berlin") it says modification date
"2015-06-22 01:53:28". Hence, there is a 6 hour difference between the
two time-zones

I use the script provided here:
http://blog.revolutionanalytics.com/2009/06/converting-time-zones.html

pb.txt <- "2015-06-22 01:53:28" #modification date as shown on my
computer (timezone
"Europe/Berlin")

pb.date <- as.POSIXct(pb.txt, tz="Europe/London")

pb.date <- as.POSIXct(pb.txt, tz="America/Toronto")#timezone of
origin video camera location

format(pb.date, tz=local.time,usetz=TRUE) #formats the mtime to data and time
when the video was taken

[1] "2015-06-22 07:53:28 CEST" # the time is correct but the date is
wrong as it has added 6 hours rather than subtracting.

I find working with different time-zones to be difficult, I hope I managed to
formulate an understandable question.

Regards,

Kes

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.