I have a datetime supplied in the following format:
ex <-2008123118
and am trying to convert it to datetime format. I try:
mytime2 <- as.POSIXct(ex, format = "%Y%m%d%H")
but receive the error:
Error in as.POSIXct.numeric(ex, format = "%Y%m%d%H") :
'origin' must be supplied
The error seems straightfoward, but the only issue is what if I don't know the origin. For example, this part of my code will go into a much larger code that will process a number of files.
I would like my example to return:
2008-12-31 18:00
Is that possible?
There are two versions of as.POSIXct working behind the scenes, as.POSIXct.numeric and as.POSIXct.character, and you have tried to call both of them at once. Because that value is coming in as "numeric" it gets passed to as.POSIXct.numeric and that is actually the cause of the error here, because as.POSIXct.numeric has no detection algorithm for date-like values and also has no "format" parameter. Coerce it to "character and all is well:
> ex <-2008123118
> mytime2 <- as.POSIXct(as.character(ex), format = "%Y%m%d%H")
> mytime2
[1] "2008-12-31 18:00:00 PST"
Here is an example with lubridate with the ymd_h function:
library(lubridate)
ymd_h(ex)
[1] "2008-12-31 18:00:00 UTC"
here a base R solution
strptime(ex, format = "%Y%m%d%H")
[1] "2008-12-31 18:00:00 CET"
You can try the following code, in base R:
> ex <-2008123118
> as.POSIXct(strptime(ex, format = "%Y%m%d%H")) #this gives you additional seconds
"2008-12-31 18:00:00 EST"
> strftime(as.POSIXct(strptime(ex, format = "%Y%m%d%H")), format = "%Y-%m-%d %H:%M") #this gives your desired format
"2008-12-31 18:00"
Hope this helps.
Related
I have a Time column in my df with value 1.01.2016 0:00:05. I want it without the seconds and therefore used df$Time <- as.POSIXct(df$Time, format = "%d.%m.%Y :%H:%M", tz = "Asia/Kolkata"). But I get NA value. What is the problem here?
I suspect there are two things working here: the storage of a time object (POSIXt), and the representation of that object.
The string you present is (I believe) not a proper POSIXt (whether POSIXct or POSIXlt) object for R, which means it is just a character string. In that case, you can remove it with:
gsub(':[^:]*$', '', '1.01.2016 0:00:05')
# [1] "1.01.2016 0:00"
However, that is still just a string, not a date or time object. If you parse it into a time-object that R knows about:
as.POSIXct("1.01.2016 0:00:05", format = "%d.%m.%Y %H:%M:%S", tz = "Asia/Kolkata")
# [1] "2016-01-01 00:00:05 IST"
then you now have a time object that R knows something about ... and it defaults to representing it (printing it on the console) with seconds-precision. Typically, all that is available to change for the console-printing is the precision of the seconds, as in
options("digits.secs")
# $digits.secs
# NULL
Sys.time()
# [1] "2018-06-26 18:21:06 PDT"
options("digits.secs"=3)
Sys.time()
# [1] "2018-06-26 18:21:10.090 PDT"
then you can get more. But alas, I do know think there is an R-option to say "always print my POSIXt objects in this way". So your only choice is (at the point where you no longer need it to be a time-like object) to change it back into a string with no time-like value:
x <- as.POSIXct("1.01.2016 0:00:05", format = "%d.%m.%Y %H:%M:%S", tz = "Asia/Kolkata")
x
# [1] "2016-01-01 00:00:05 IST"
?strptime
# see that day-of-month can either be "%d" for 01-31 or "%e" for 1-31
format(x, format="%e.%m.%Y %H:%M")
# [1] " 1.01.2016 00:00"
(This works equally well for a vector.)
Part of me suggests convert to POSIXt and back to string as opposed to my gsub example because using as.POSIXct will tell you when the string does not match the date-time-like object you are expecting, whereas gsub will happily do something wrong or nothing.
Try asPOSIXlt:
> test <- "1.01.2016 0:00:05"
> as.POSIXlt(test, "%d.%m.%Y %H:%M:%S", tz="Asia/Kolkata")
[1] "2016-01-01 00:00:05 IST"
I have a DateTime object in R.
tempDateTime<-as.POSIXct("2017-07-13 01:40:00 MDT")
class(tempDateTime)
[1] "POSIXct" "POSIXt"
I would like to drop the minutes from the DateTime object. ie have "2017-07-13 01:00:00 MDT"
Is there a simple way to do this?
In Base R
trunc(tempDateTime, units = "hours")
# "2017-07-13 01:00:00 AEST"
This works because the round function in base R has a method to handle POSIX objects.
From ?round.POSIXt
Round or truncate date-time objects.
As #Thelatemail points out, this returns a POSIXlt object, so you may want to wrap the result in as.POSIXct() again.
Another note, POSIXct is an object that stores the number of seconds since "1970-01-01 00:00:00" (the Unix epoch).
as.numeric(tempDateTime)
# 1499874000
So the manual way to round-down the hours would be
as.POSIXct(floor(as.numeric(tempDateTime) / 3600) * 3600, origin = "1970-01-01")
Try this:
library(lubridate)
> floor_date(tempDateTime, "hour")
[1] "2017-07-13 01:00:00 PDT"
I coded the below in R and I want to see the hour,time and second format.
However, when I ran the code, it just shows the year,month and day even though I specified the format correctly.
> val <- 12016539307200
> valD <- as.Date(as.POSIXct(val, origin="1970-01-01"),format="%Y%m%d %H%M%S")
> valD
[1] "382758-12-22"
Could you give me a way to solve this issue?
Because it is a Date object, representing a calendar date. To have an object representing time, keep it in POSIXct:
> val <- 12016539307200
> valD <- as.POSIXct(val, origin="1970-01-01", tz = "UTC")
> valD
[1] "382758-12-22 01:20:00 UTC"
If it contains milliseconds, you go for the following:
as.POSIXct(val/1000, origin="1970-01-01")
"2350-10-16 09:35:07 CEST"
or
library(anytime)
anytime(12016539307200/1000)
"2350-10-16 09:35:07 CEST"
I have two columns of differently formatted date strings that I need to make the same format,
the first is in the form:
vt_dev_date = "6/20/2016 7:45"
the second is in the form
vt_other = "2016-06-14 20:21:29.0"
If could get them both in the same form down to the minute that would be great. I have tried
strptime(vt_dev_date,format = "%Y-%m-%d %H:%M")
strptime(vt_other,"%Y-%m-%d %H:%M")
and for the second one, it works and I get
"2016-06-14 20:21:00 EDT"
But for the first string, it seems that because the month and hour are not padded with zeros, none of the formating tricks will work, becuase if I try
test_string <- "06/20/2016 07:45"
strptime(test_string,format = "%m/%d/%Y %H:%M")
[1] "2016-06-20 07:45:00 EDT"
It works, but I dont think going through every row in the column and padding each date is a great option. Any help would be appreciated.
Thanks,
josh
How about using lubridate , as follows :
library(lubridate)
x <- c("6/20/2016 7:45","2016-06-14 20:21:29.0")
> x
[1] "6/20/2016 7:45" "2016-06-14 20:21:29.0"
> parse_date_time(x, orders = c("mdy hm", "ymd hms"))
[1] "2016-06-20 07:45:00 UTC" "2016-06-14 20:21:29 UTC"
>
I have a POSIXct object and would like to change it's tz attribute WITHOUT R to interpret it (interpret it would mean to change how the datetime is displayed on the screen).
Some background: I am using the fasttime package from S.Urbanek, which take strings and cast it to POSIXct very quickly. Problem is that the string should represent a datetime in "GMT" and it's not the case of my data.
I end up with a POSIXct object with tz=GMT, in reality it is tz=GMT+1, if I change the timezone with
attr(datetime, "tzone") <- "Europe/Paris";
datetime <- .POSIXct(datetime,tz="Europe/Paris");
then it will be "displayed" as GMT+2 (the underlying value never change).
EDIT: Here is an example
datetime=as.POSIXct("2011-01-01 12:32:23.234",tz="GMT")
attributes(datetime)
#$tzone
#[1] "GMT"
datetime
#[1] "2011-01-01 12:32:23.233 GMT"
How can I change this attribute without R to interpret it aka how can I change tzone and still have datetime displayed as "2011-01-01 12:32:23.233" ?
EDIT/SOLUTION, #GSee's solution is reasonably fast, lubridate::force_tz very slow
datetime=rep(as.POSIXct("2011-01-01 12:32:23.234",tz="GMT"),1e5)
f <- function(x,tz) return(as.POSIXct(as.numeric(x), origin="1970-01-01", tz=tz))
> system.time(datetime2 <- f(datetime,"Europe/Paris"))
user system elapsed
0.01 0.00 0.02
> system.time(datetime3 <- force_tz(datetime,"Europe/Paris"))
user system elapsed
5.94 0.02 5.98
identical(datetime2,datetime3)
[1] TRUE
To change the tz attribute of a POSIXct variable it is not best practice to convert to character or numeric and then back to POSIXct. Instead you could use the force_tz function of the lubridate package
library(lubridate)
datetime2 <- force_tz(datetime, tzone = "CET")
datetime2
attributes(datetime2)
EDITED:
My previous solution was passing a character value to origin (i.e.origin="1970-01-01"). That only worked here because of a bug (#PR14973) that has now been fixed in R-devel.
origin was being coerced to POSIXct using the tz argument of the as.POSIXct call, and not "GMT" as it was documented to do. The behavior has been changed to match the documentation which, in this case, means that you have to specify your timezone for both the origin and the as.POSIXct call.
datetime
#[1] "2011-01-01 12:32:23.233 GMT"
as.POSIXct(as.numeric(datetime), origin=as.POSIXct("1970-01-01", tz="Europe/Paris"),
tz="Europe/Paris")
#[1] "2011-01-01 12:32:23.233 CET"
This will also works in older versions of R.
An alternative to the lubridate package is via conversion to and back from character type:
recastTimezone.POSIXct <- function(x, tz) return(
as.POSIXct(as.character(x), origin = as.POSIXct("1970-01-01"), tz = tz))
(Adapted from GSee's answer)
Don't know if this is efficient, but it would work for time zones with daylight savings.
Test code:
x <- as.POSIXct('2003-01-03 14:00:00', tz = 'Etc/UTC')
x
recastTimezone.POSIXct(x, tz = 'Australia/Melbourne')
Output:
[1] "2003-01-03 14:00:00 UTC"
[1] "2003-01-03 14:00:00 AEDT" # Nothing is changed apart from the time zone.
Output if I replaced as.character() by as.numeric() (as GSee had done):
[1] "2003-01-03 14:00:00 UTC"
[1] "2003-01-03 15:00:00 AEDT" # An hour is added.