Is there a way to convert Sys.time to New york time zone in R?. I tried with following, but did not work
as.POSIXct(Sys.time(), tz="EDT")
Can anyone help?
When you call Sys.time(), the time zone is already included in the string:
Sys.time()
#> [1] "2020-09-18 08:56:56 BST"
If you want to convert that time to a different timezone, you can set its "tzone" attribute:
`attr<-`(as.POSIXct(Sys.time()), "tzone", "EST")
#> [1] "2020-09-18 02:57:23 EST"
My system doesn't recognise "EDT" as a named time zone. I have to do:
`attr<-`(as.POSIXct(Sys.time()), "tzone", "America/New_York")
#> [1] "2020-09-18 03:59:55 EDT"
You can display time in any time-zone using format :
time <- Sys.time()
format(time, tz="America/New_York",usetz=TRUE)
#[1] "2020-09-18 03:59:39 EDT"
#this works too
format(time, tz="US/Eastern",usetz=TRUE)
#[1] "2020-09-18 03:59:39 EDT"
Related
This question already has an answer here:
Issue with the format in anytime package
(1 answer)
Closed yesterday.
I am trying to convert a string of date and time in R using anytime() function. The string have the format 'date-month-year hour-minute-second'. It seems that the anytime() function does not work for a few cases, as shown in the example below.
library(lubridate)
x1<-"03-01-2019 01:00:00"
x2<-"23-01-2019 17:00:00"
anytime(x1)
[1] "2019-03-01 01:00:00 CET"
anytime(x2)
[1] NA
I am trying to figure out how to get rid of this problem. Thanks for your help :)
You can use addFormats() to add a specific format to the stack known and used by anytime() (and/or anydate())
> library(anytime)
> addFormats("%d-%m-%Y %H:%M:%S")
> anytime(c("03-01-2019 01:00:00", "23-01-2019 17:00:00"))
[1] "2019-01-03 01:00:00 CST" "2019-01-23 17:00:00 CST"
>
As explained a few times before on this site, the xx-yy notation is ambiguous and interpreted differently in different parts of the world.
So anytime is guided by use as the separator: / is more common in North America so we use "mm/dd/yyy". On the other hand a hyphen is more common in Europe so the "dd-mm-yyyy" starts that way. You can use getFormats() to see the formats in anytime(). In a fresh session:
> head(getFormats(), 12) ## abbreviated for display here
[1] "%Y-%m-%d %H:%M:%S%f" "%Y-%m-%e %H:%M:%S%f" "%Y-%m-%d %H%M%S%f"
[4] "%Y-%m-%e %H%M%S%f" "%Y/%m/%d %H:%M:%S%f" "%Y/%m/%e %H:%M:%S%f"
[7] "%Y%m%d %H%M%S%f" "%Y%m%d %H:%M:%S%f" "%m/%d/%Y %H:%M:%S%f"
[10] "%m/%e/%Y %H:%M:%S%f" "%m-%d-%Y %H:%M:%S%f" "%m-%e-%Y %H:%M:%S%f"
>
You can use it without the head() to see all.
An alternative approach could be using parsedate package:
library(parsedate)
> parsedate::parse_date(x1)
[1] "2019-03-01 01:00:00 UTC"
> parsedate::parse_date(x2)
[1] "2019-01-23 17:00:00 UTC"
Trying to get current date in a POSIXct class. I have tried the following:
as.POSIXct(Sys.Date(), format = "%m/%d/%y", tz = "EST")
and got
[1] "2021-02-12 19:00:00 EST"
and I wish to only get the date without the time but in POSIXct class. For instance:
[1] "2021-02-12"
Convert the Date class object to character first:
as.POSIXct(format(Sys.Date()))
## [1] "2021-02-13 EST"
Even shorter is:
trunc(Sys.time(), "day")
## [1] "2021-02-13 EST"
Note:
POSIXct objects are stored internally as seconds since the Epoch and not as separate date and time so they always have times; however, if the time is midnight as it is here then it does not display when printed using the default formatting.
if you only need the Date it is normally better to use Date class since using POSIXct class can result in subtle time zone errors if you are not careful and there is typically no reason to expose yourself to that potential if you don't need to.
if you change the session's time zone then it won't display without the time because midnight in one time zone is not midnight other time zones.
x <- as.POSIXct(format(Sys.Date()))
x
## [1] "2021-02-13 EST"
# change time zone
Sys.setenv(tz = "GMT")
x
## [1] "2021-02-13 05:00:00 GMT"
# change back
Sys.setenv(tz = "")
x
## [1] "2021-02-13 EST"
I am trying to get the last minute of yesterday using Sys.Date() in Posix time.
force_tz(as.POSIXlt(Sys.Date()-1), tz = 'America/New_York') + 86399
# [1] "2018-01-12 23:59:59 EST"
CORRECT
force_tz(as.POSIXct(Sys.Date()-1), tz = 'America/New_York') + 86399
# [1] "2018-01-12 15:59:59 EST"
INCORRECT
Sys.Date()
# [1] "2018-01-13"
Why does as.Posixct and as.Posixlt return two different values using Sys.Date() and why is the difference 8 hours even after applying force_tz from lubridate ?
As ever, debugonce is your friend. Running debugonce(force_tz), you can see that the difference in output comes from when force_tz hits the branches checking first is.POSIXct(time) (in which case the default tzone = "" is applied); in the POSIXlt case, the default branch is hit, where as.POSIXct is applied to time and tz(time) (which comes out as UTC for a POSIXlt object) is used as the time zone.
This comes down to something subtle happening; from ?as.POSIXlt.Date:
Dates without times are treated as being at midnight UTC.
Hence
tz(as.POSIXlt(Sys.Date()-1))
# [1] "UTC"
But
tz(as.POSIXct(Sys.Date()-1))
# [1] ""
What's peculiar is this can't be overridden -- as.POSIXlt.Date doesn't accept a tz argument:
formals(as.POSIXlt.Date)
# $x
# $...
If you want to use POSIXct, how about the following?
force_tz(as.POSIXct(sprintf('%s 00:00:00', Sys.Date())), 'America/New_York') - 1L
# [1] "2018-01-12 23:59:59 EST"
There is something I don't understand. I simply try to convert a date in an other time zone. The date is in the 8601-ISO format. I followed this.
pb.txt <- "2012-09-11T21:23:20Z"
pb.date <- as.POSIXct(pb.txt, tz="UTC")
format(pb.date, tz="WEST",usetz=TRUE)
[1] "2012-09-11 WEST"
Why only the date appears and not anymore the timestamp ?
I tried also :
pb.date <- as.POSIXct(pb.txt, origin=ISOdatetime(2012,09,11,21,23,20))
format(pb.date, tz="WEST",usetz=TRUE)
[1] "2012-09-10 22:00:00 WEST
It's better, but the timestamp is rounded. How to convert perfectly an 8601-ISO datetime ?
Use the correct format:
as.POSIXct(pb.txt, "%Y-%m-%dT%H:%M:%S", tz="UTC")
[1] "2012-09-11 21:23:20 UTC"
In addition to #JoshuaUlrich answer, don't use daylight saving time timezone: use regular time zone, the system will convert automatically if the day chosen falls during summer time.
Given pb.date <- as.POSIXct(pb.txt, "%Y-%m-%dT%H:%M:%S", tz="UTC") as per Joshua's answer, this fails:
format(pb.date, tz="WEST",usetz=TRUE)
[1] "2012-09-11 21:23:20 UTC"
but this doesn't:
format(pb.date, tz="WET", usetz=TRUE)
[1] "2012-09-11 22:23:20 WEST"
I need to use as.Date on the index of a zoo object. Some of the dates are in BST and so when converting I lose a day on (only) these entries. I don't care about one hour's difference or even the time part of the date at all, I just want to make sure that the dates displayed stay the same. I'm guessing this is not very hard but I can't manage it. Can somebody help please?
class(xtsRet)
#[1] "xts" "zoo"
index(xtsRet)
#[1] "2007-07-31 BST" "2007-08-31 BST" "2007-09-30 BST" "2007-10-31 GMT"
class(index(xtsRet))
#[1] "POSIXt" "POSIXct"
index(xtsRet) <- as.Date(index(xtsRet))
index(xtsRet)
#[1] "2007-07-30" "2007-08-30" "2007-09-29" "2007-10-31"
Minimally reproducible example (not requiring zoo package):
my_date <- as.POSIXct("2007-04-01") # Users in non-UK timezone will need to
# do as.POSIXct("2007-04-01", "Europe/London")
my_date
#[1] "2017-04-01 BST"
as.Date(my_date)
#[1] "2017-03-31"
Suppose we have this sample data:
library(zoo)
x <- as.POSIXct("2000-01-01", tz = "GMT")
Then see if any of these are what you want:
# use current time zone
as.Date(as.character(x, tz = ""))
# use GMT
as.Date(as.character(x, tz = "GMT"))
# set entire session to GMT
Sys.setenv(TZ = "GMT")
as.Date(x)
Also try "BST" in place of "GMT" and note the article on dates and times in R News 4/1 .
You can offset the POSIX objects so its not based around midnight. 1 hour (3600 secs) should be sufficient:
d <- as.POSIXct(c("2007-07-31","2007-08-31","2007-09-30","2007-10-31"))
d
[1] "2007-07-31 BST" "2007-08-31 BST" "2007-09-30 BST" "2007-10-31 GMT"
as.Date(d)
[1] "2007-07-30" "2007-08-30" "2007-09-29" "2007-10-31"
as.Date(d+3600)
[1] "2007-07-31" "2007-08-31" "2007-09-30" "2007-10-31"
I would suggest using as.POSIXlt to convert to a date object, wrapped in as.Date:
d <- as.POSIXct(c("2007-07-31","2007-08-31","2007-09-30","2007-10-31"))
d
[1] "2007-07-31 BST" "2007-08-31 BST" "2007-09-30 BST" "2007-10-31 GMT"
as.Date(as.POSIXlt(d))
[1] "2007-07-31" "2007-08-31" "2007-09-30" "2007-10-31"
Achieves the same thing as the +3600 above, but slightly less of a hack