[R] Time format lagging issue

[MacQueen, Don]

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]]
>
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