[R] Time rather than dates?
Using strptime() and other functions for dates has been very helpful with
the kind of data I often work with. However, I haven't found out how time
as such should be specified. All my attempts result in time *and* date:
>treatment_time<-c("01:02:03","02:03:04") # hours:minutes:seconds
>time.2<-strptime(treatment_time,format="%H:%M:%S")
>time.2
[1] "1900-01-01 01:02:03" "1900-01-01 02:03:04"
Why the 1900-...? I had hoped for some easy conversion from time to
numeric data and possibly back. Assistance would be appreciated.
Robert
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Re: [R] Time rather than dates?
On Tue, 30 May 2006, Robert Lundqvist wrote:
> Using strptime() and other functions for dates has been very helpful with
> the kind of data I often work with. However, I haven't found out how time
> as such should be specified. All my attempts result in time *and* date:
>
>> treatment_time<-c("01:02:03","02:03:04") # hours:minutes:seconds
>> time.2<-strptime(treatment_time,format="%H:%M:%S")
>
>> time.2
> [1] "1900-01-01 01:02:03" "1900-01-01 02:03:04"
>
> Why the 1900-...? I had hoped for some easy conversion from time to
> numeric data and possibly back. Assistance would be appreciated.
You asked to print a datetime object of class POSIXlt, and unspecified
fields are set to their earliest values. But printing is only part of the
story.
What do you actually want from this?
3600*time.2$hour + 60*time.2$min + time.2$sec
gives you the number of seconds since midnight, for example. See
?DateTimeClasses
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax: +44 1865 272595
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Re: [R] Time rather than dates?
Try using the "times" class in the chron package.
> library(chron)
> times(c("01:02:03","02:03:04"))
[1] 01:02:03 02:03:04
On 5/30/06, Robert Lundqvist <[EMAIL PROTECTED]> wrote:
> Using strptime() and other functions for dates has been very helpful with
> the kind of data I often work with. However, I haven't found out how time
> as such should be specified. All my attempts result in time *and* date:
>
> >treatment_time<-c("01:02:03","02:03:04") # hours:minutes:seconds
> >time.2<-strptime(treatment_time,format="%H:%M:%S")
>
> >time.2
> [1] "1900-01-01 01:02:03" "1900-01-01 02:03:04"
>
> Why the 1900-...? I had hoped for some easy conversion from time to
> numeric data and possibly back. Assistance would be appreciated.
>
> Robert
>
> __
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>
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Re: [R] Time rather than dates?
Hi
Which version of R do you use?
Version 2.3.1 beta (2006-05-23 r38179)
> treatment_time<-c("01:02:03","02:03:04")
> strptime(treatment_time,format="%H:%M:%S")
[1] "2006-05-30 01:02:03" "2006-05-30 02:03:04"
> ttt<-strptime(treatment_time,format="%H:%M:%S")
For changing format of POSIX variables use format
> format(ttt, "%H:%M")
[1] "01:02" "02:03"
Maybe also consult locale setting.
HTH
Petr
On 30 May 2006 at 14:16, Robert Lundqvist wrote:
To: r-help@stat.math.ethz.ch
From: Robert Lundqvist <[EMAIL PROTECTED]>
Date sent: Tue, 30 May 2006 14:16:29 +0200
Subject:[R] Time rather than dates?
Send reply to: [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
<mailto:[EMAIL PROTECTED]>
> Using strptime() and other functions for dates has been very helpful
> with the kind of data I often work with. However, I haven't found out
> how time as such should be specified. All my attempts result in time
> *and* date:
>
> >treatment_time<-c("01:02:03","02:03:04") # hours:minutes:seconds
> >time.2<-strptime(treatment_time,format="%H:%M:%S")
>
> >time.2
> [1] "1900-01-01 01:02:03" "1900-01-01 02:03:04"
>
> Why the 1900-...? I had hoped for some easy conversion from time to
> numeric data and possibly back. Assistance would be appreciated.
>
> Robert
>
> __
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
Petr Pikal
[EMAIL PROTECTED]
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Re: [R] Time rather than dates?
On Tue, 30 May 2006, Petr Pikal wrote:
> Which version of R do you use?
> Version 2.3.1 beta (2006-05-23 r38179)
>
>> treatment_time<-c("01:02:03","02:03:04")
>> strptime(treatment_time,format="%H:%M:%S")
> [1] "2006-05-30 01:02:03" "2006-05-30 02:03:04"
>From ?strptime
If the date string does not specify the date completely, the
returned answer may be system-specific. The most common behaviour
is to assume that unspecified seconds, minutes or hours are zero,
and a missing year, month or day is the current one.
which explains the different answer. Neither of you told us your OS.
>> ttt<-strptime(treatment_time,format="%H:%M:%S")
>
> For changing format of POSIX variables use format
>> format(ttt, "%H:%M")
> [1] "01:02" "02:03"
>
> Maybe also consult locale setting.
>
> HTH
> Petr
>
>
>
> On 30 May 2006 at 14:16, Robert Lundqvist wrote:
>
> To: r-help@stat.math.ethz.ch
> From: Robert Lundqvist <[EMAIL PROTECTED]>
> Date sent:Tue, 30 May 2006 14:16:29 +0200
> Subject: [R] Time rather than dates?
> Send reply to:[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED]>
>
>> Using strptime() and other functions for dates has been very helpful
>> with the kind of data I often work with. However, I haven't found out
>> how time as such should be specified. All my attempts result in time
>> *and* date:
>>
>>> treatment_time<-c("01:02:03","02:03:04") # hours:minutes:seconds
>>> time.2<-strptime(treatment_time,format="%H:%M:%S")
>>
>>> time.2
>> [1] "1900-01-01 01:02:03" "1900-01-01 02:03:04"
>>
>> Why the 1900-...? I had hoped for some easy conversion from time to
>> numeric data and possibly back. Assistance would be appreciated.
>>
>> Robert
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax: +44 1865 272595
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R-help@stat.math.ethz.ch mailing list
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