Very few attachment file types are allowed through the mailing list, and
yours did not make it.
I noticed that your format strings did not appear consistent... see the
format string I use below, and make sure the characters between the
numeric parts of your format are correct for your case. Did you read
the help file ?strptime ?
Note that there are two steps... importing the character data to a POSIXct
type, and then choosing how you want to display those instants of time in
whatever time zones you wish. That is, regardless of time zone, the
POSIXct value represents the same instant of time regardless of time zone
you want to display it in, while POSIXlt will in general have different
internal representations that match the external representations.
Note that you really do need to read ?timezone, because the below code
only works if your system understands the "GMT" and "Australia/Darwin"
timezones, and that is operating-system-specific behavior. This was
successfully run on Ubuntu... you did not mention your operating system.
tst <- "2014-12-25 00:00" # GMT
tstct <- as.POSIXct( tst, format="%Y-%m-%d %H:%M", tz="GMT" )
tstct
[1] "2014-12-25 GMT"
unclass(tstct)
[1] 1419465600
attr(,"tzone")
[1] "GMT"
tstlt <- as.POSIXlt( tstct, tz="Australia/Darwin" )
tstlt
[1] "2014-12-25 09:30:00 ACST"
unclass(tstlt)
$sec
[1] 0
$min
[1] 30
$hour
[1] 9
$mday
[1] 25
$mon
[1] 11
$year
[1] 114
$wday
[1] 4
$yday
[1] 358
$isdst
[1] 0
$zone
[1] "ACST"
$gmtoff
[1] 34200
attr(,"tzone")
[1] "Australia/Darwin" "ACST" "ACDT"
tstct2 <- as.POSIXct( tstlt )
tstct2
[1] "2014-12-25 09:30:00 ACST"
unclass(tstct2)
[1] 1419465600
attr(,"tzone")
[1] "Australia/Darwin"
On Sun, 28 Dec 2014, Faranak Golestaneh wrote:
Dear Friends, I?ve just started using R. I am working on a database
containing date-time as well as numeric values. Firstly I have changed the
class of the data/time column from factor to POSIXlt. Time and date are
based on UTC time but I need to change them to a local time ( not my local
time, my zone is Singapore but the data are from Australia) so I need to
change the time and date to Australia time say e.g AEST. I tried one way or
another but all failed. The following is example of the command I used.
Also one of my .CSV files is attached.
Data_Power <- read.table("train15.csv",header = TRUE, sep = ",", row.names
= NULL);
Date_clm=Data_Power$TIMESTAMP;
Date_original <- strptime(Date_clm, "%Y %m %d %H:%M", tz="GMT")
Date_local =format(Date_original, format="%c", tz="America/New_York")
Date_local <- strptime(Date_original, "%Y %m %d %H:%M +0800")
Date_local=as.POSIXlt(Date_original, "Australia/Darwin")
Date_local=as.POSIXlt(Date_original, " AEST ")
I would be so thankful if you help me out. Thanks
Cheers,
Faranak
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