I need to change my time zone from EST to UTC using the base R functions. I wrote this code but the problem is that although during the daylight saving time the time difference between these two time zones should be 4 hours, the function does not take it into account. Therefore, during the whole year the time difference equals to 5. My dataset is here.
data <- read.csv("data.csv")
data1 <- data
attributes(data1$time)$tzone
data1$time <- as.POSIXct(data1$time, format="%m/%d/%Y %H:%M:%S", tz="EST")
attributes(data1$time)$tzone
attr(data1$time, "tzone") <- "UTC"
attributes(data1$time)$tzone
Using tz = "EST" means you are specifying Eastern standard time, which is only active in autumn/winter. As indicated by #r2evans, tz = "US/Eastern" or tz = "America/New_York" specifies that the time should switch between EST and EDT (Eastern daylight time) on the appropriate dates.
Related
I am trying to convert UTC time to local standard time. I have found many functions which convert to Local Daylight Time, but I was not successful in getting the standard time. Right now, I have the following code which converts to local daylight time at my specific timezone:
pb.date <- as.POSIXct(date,tz="UTC")
format(pb.date, tz="timeZone",usetz=TRUE)
I would appreciate any help.
First, POSIXct date-times are always UCT internally. The print.POSIXt and format.POSIXt methods will appropriately make the TZ shift on output from their internal representations:
pb.date <- as.POSIXct(Sys.Date())
Sys.Date()
#[1] "2015-07-09"
So that was midnight of the current date in Greenwich:
format(pb.date, tz="America/Los_Angeles",usetz=TRUE)
#[1] "2015-07-08 17:00:00 PDT"
When it's midnight in Greenwich, it's 5PM Daylight Time in the previous day on the Left Coast of the US. You need to use the correct character values for your TZ (and your OS) both of which at the moment are unspecified.
The US Pacific timezone is 8 hours behind GMT (in winter months) so you can use a timezone that is Standard/Daylight-agnostic:
> format(pb.date,usetz=TRUE, tz="Etc/GMT+8")
[1] "2015-07-08 16:00:00 GMT+8"
(Notice the reversal of + with "behind" and - with "ahead".)
I know this question has an accepted answer, but in case anyone comes along and this can help. I needed a function to convert UTC times to MTN time (Server is in UTC, we operate in MTN).
Not sure why, but needed to force it to UTC/GMT first and the convert it to MTN. However it does work
mtn_ts = function(utcTime){
library(lubridate)
toTz = "us/mountain"
utcTime = force_tz(utcTime,tzone= 'GMT')
dt = as.POSIXct(format(utcTime,tz = toTz,origin ='GMT', usetz=TRUE))
dt = force_tz(dt,tzone= toTz)
return(dt)
}
mtn_ts(as.POSIXct("2021-09-27 14:48:51.000000000"))
I am trying to convert UTC time to local standard time. I have found many functions which convert to Local Daylight Time, but I was not successful in getting the standard time. Right now, I have the following code which converts to local daylight time at my specific timezone:
pb.date <- as.POSIXct(date,tz="UTC")
format(pb.date, tz="timeZone",usetz=TRUE)
I would appreciate any help.
First, POSIXct date-times are always UCT internally. The print.POSIXt and format.POSIXt methods will appropriately make the TZ shift on output from their internal representations:
pb.date <- as.POSIXct(Sys.Date())
Sys.Date()
#[1] "2015-07-09"
So that was midnight of the current date in Greenwich:
format(pb.date, tz="America/Los_Angeles",usetz=TRUE)
#[1] "2015-07-08 17:00:00 PDT"
When it's midnight in Greenwich, it's 5PM Daylight Time in the previous day on the Left Coast of the US. You need to use the correct character values for your TZ (and your OS) both of which at the moment are unspecified.
The US Pacific timezone is 8 hours behind GMT (in winter months) so you can use a timezone that is Standard/Daylight-agnostic:
> format(pb.date,usetz=TRUE, tz="Etc/GMT+8")
[1] "2015-07-08 16:00:00 GMT+8"
(Notice the reversal of + with "behind" and - with "ahead".)
I know this question has an accepted answer, but in case anyone comes along and this can help. I needed a function to convert UTC times to MTN time (Server is in UTC, we operate in MTN).
Not sure why, but needed to force it to UTC/GMT first and the convert it to MTN. However it does work
mtn_ts = function(utcTime){
library(lubridate)
toTz = "us/mountain"
utcTime = force_tz(utcTime,tzone= 'GMT')
dt = as.POSIXct(format(utcTime,tz = toTz,origin ='GMT', usetz=TRUE))
dt = force_tz(dt,tzone= toTz)
return(dt)
}
mtn_ts(as.POSIXct("2021-09-27 14:48:51.000000000"))
Currently we are implementing some sort of direct marketing
We send an SMS (timestamp) on a certain day from a certain country within Europe and then receive a response from a customer in the local country if they are interested in the product
I have a sample data set for two months, of SMS's sent and Responses received (if at all). The end goal is , I want to calculate the time difference in hours between the sent time and the response time factoring in Time Zones and Day Light Savings
The file i received has the time stamps in character format. I wish to convert them to dates of their local timezones, convert them to a standard zone and calculate the hours difference
I have tried the methods below to just create the conversion but it comes back with NA.
Any help would be greatly appreciated
as.POSIXlt("12/02/2015 11:23", tz = "Europe/London")
strptime("12/02/2015 11:23", "%d/%m/%Y %h:%m")
as.Date("12/02/2015 11:23","%d/%m/%y %h:%m")
Note that you do not say if you are using 24-hour or 12-hour clock, but given that you do not have AM/PM, I am going to assume the former:
strptime("12/02/2015 11:23 AM", "%d/%m/%Y %I:%M %p", tz = "Europe/London") #12-hour
strptime("12/02/2015 11:23", "%d/%m/%Y %H:%M", tz = "Europe/London") # 24-hour
t1 <- strptime("2015-02-17 12:20:00", format = "%Y-%m-%d %H:%M:%S", tz = "America/Chicago")
t2 <- strptime("2015-03-13 15:00:00", format = "%Y-%m-%d %H:%M:%S", tz = "America/Chicago")
as.numeric(abs(difftime(t1, t2, units = "mins", tz = "America/Chicago")))
The above returns 34,660 while Excel and http://www.timeanddate.com/date/duration.html both return 34,720. R recognizes t1 as CST and t2 as CDT due to daylight savings on 3/8/15. I wanted to confirm that R is correct, while these other two sources are not.
Depends if you want to take into account local daylight savings, or if these times are two points in time irrelevant of local shifts. Excel and that site are just taking the exact difference between those two times, discarding daylight savings - e.g. R can get the same result by changing the timezones to UTC, which doesn't observe daylight saving:
difftime(as.POSIXct("2015-03-13 15:00:00",tz="UTC"),
as.POSIXct("2015-02-17 12:20:00",tz="UTC"), units="mins")
# Time difference of 34720 mins
If I'm sitting in Chicago with a stopwatch and counting the minutes difference between when a local clock in the pub says "2015-02-17 12:20:00" and then hits "2015-03-13 15:00:00", I'd count 60 minutes less as the clock got wound forward an hour for daylight savings while I was counting.
I have a series of character timestamps in R. When I change their class to POSIXct using intuitive methods, R assigns the ambiguous timezone EST.
For example:
as.POSIXct("2012-08-06 15:32:00")
as.POSIXct("2012-08-06 15:32:00", tz = "Australia/Brisbane")
as.POSIXct("2012-08-06 15:32:00", tz = "")
all produce the same output on my two (Mac and Windows) boxes:
"2012-08-06 15:32:00 EST"
The problem here is EST could be any number of timezones: Eastern Standard Time in the USA, or Australian Eastern Standard Time, or another timezone in Canada (from ?timezone):
Beware that some of these designations may not be what you think: in
particular EST is a time zone used in Canada without daylight savings
time, and not EST5EDT nor (Australian) Eastern Standard Time.
There is a method to set the timezone which avoids this EST label. It is alluded to, but not fully explained in the R ?timezone help. Setting x as the time of the Curiosity landing on Mars as reported by an Australian news service:
x <- as.POSIXct("2012-08-06 15:32:00", tz = "Etc/GMT-10")
x
"2012-08-06 15:32:00 GMT-10"
And we can test that this is correct by converting it to a US timezone and checking with a Californian news report:
y <- format(x, tz = "America/Los_Angeles")
y
"2012-08-05 22:32:00"
If using this Etc/GMT+n or Etc/GMT-n notation, please beware of the following caveat from ?timezone :
Many systems support timezones of the form GMT+n and GMT-n, which are
at a fixed offset from UTC (hence no DST). Contrary to some usage (but
consistent with names such as PST8PDT), negative offsets are times
ahead of (east of) UTC, positive offsets are times behind (west of)
UTC.
The 1st and 3rd lines in your first example produce the same output because tz="" is the default for as.POSIXct. The second line is more interesting because the timezone is explicitly defined.
But note that "EST" is only how the timezone is printed by default. The tzone attribute is still unambiguous.
R> x <- as.POSIXct("2012-08-06 15:32:00", tz="Australia/Brisbane")
R> x
[1] "2012-08-06 15:32:00 EST"
R> attr(x, "tzone")
[1] "Australia/Brisbane"