[R] Time format lagging issue

[Bhaskar Mitra]

Thanks for all your feedbacks. This is helpful.

My apologies for any inconvenience due to asterisks.

Thanks,
Bhaskar

On Wed, Aug 31, 2016 at 6:09 PM, William Dunlap <wdunlap at tibco.com> wrote:

> That
>   tmp1 - 30*60
> can also be done as
>   tmp1 - as.difftime(30, units="mins")
> so you don't have to remember that the internal representation of POSIXct
> is seconds since the start of 1970.  You can choose from the following
> equivalent expressions.
>   tmp1 - as.difftime(0.5, units="hours")
>   tmp1 - as.difftime(1/2 * 1/24, units="days")
>   tmp1 - as.difftime(30*60, units="secs")
>   tmp1 - as.difftime(1/2 * 1/24 * 1/7, units="weeks")
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Wed, Aug 31, 2016 at 2:44 PM, MacQueen, Don <macqueen1 at llnl.gov> wrote:
>
>> Try following this example:
>>
>> mydf <- data.frame(t1=c('201112312230', '201112312330'))
>> tmp1 <- as.POSIXct(mydf$t1, format='%Y%m%d%H%M')
>> tmp2 <- tmp1 - 30*60
>> mydf$t2 <- format(tmp2, '%Y%m%d%H%M')
>>
>> It can be made into a single line, but I used intermediate variables tmp1
>> and tmp2 so that it would be easier to follow.
>>
>> Base R is more than adequate for this task.
>>
>> Please get rid of the asterisks in your next email. The just get in the
>> way. Learn how to send plain text email, not HTML email. Please.
>>
>>
>>
>>
>> --
>> Don MacQueen
>>
>> Lawrence Livermore National Laboratory
>> 7000 East Ave., L-627
>> Livermore, CA 94550
>> 925-423-1062
>>
>>
>>
>>
>>
>> On 8/31/16, 9:07 AM, "R-help on behalf of Bhaskar Mitra"
>> <r-help-bounces at r-project.org on behalf of bhaskar.kolkata at gmail.com>
>> wrote:
>>
>> >Hello Everyone,
>> >
>> >I am trying a shift the time series in a dataframe (df) by 30 minutes .
>> My
>> >current format looks something like this :
>> >
>> >
>> >
>> >*df$$Time 1*
>> >
>> >
>> >*201112312230*
>> >
>> >*201112312300*
>> >
>> >*201112312330*
>> >
>> >
>> >
>> >*I am trying to add an additional column of time (df$Time 2) next to
>> Time
>> >1 by lagging it by ­ 30minutes. Something like this :*
>> >
>> >
>> >*df$Time1                   **df$$Time2*
>> >
>> >
>> >*201112312230          **201112312200*
>> >
>> >*201112312300          **201112312230*
>> >
>> >*201112312330          **201112312300*
>> >
>> >*201112312330          *
>> >
>> >
>> >
>> >
>> >
>> >*Based on some of the suggestions available, I have tried this option *
>> >
>> >
>> >
>> >*require(zoo)*
>> >
>> >*df1$Time2  <- lag(df1$Time1, -1, na.pad = TRUE)*
>> >
>> >*View(df1)*
>> >
>> >
>> >
>> >*This does not however give me the desired result. I would appreciate any
>> >suggestions/advice in this regard.*
>> >
>> >
>> >*Thanks,*
>> >
>> >*Bhaskar*
>> >
>> >       [[alternative HTML version deleted]]
>> >
>> >______________________________________________
>> >R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> >https://stat.ethz.ch/mailman/listinfo/r-help
>> >PLEASE do read the posting guide
>> >http://www.R-project.org/posting-guide.html
>> >and provide commented, minimal, self-contained, reproducible code.
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

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