[R] difference between successive values

[Jim Lemon]

Hi catalin,
I think what you are trying to do is to retrieve the original
observations from the cumulated values. In that case Olivier's
suggestion will do what you want:

c(x[1],diff(x))

Jim


On Sat, Mar 5, 2016 at 1:59 AM, catalin roibu <catalinroibu at gmail.com> wrote:
> I mean the first row value
>
> În Vin, 4 mar. 2016, 16:15 Jeff Newmiller, <jdnewmil at dcn.davis.ca.us> a
> scris:
>
>> "Keep the first values" is imprecise, but mixing an absolute value with a
>> bunch of differences doesn't usually work out well.  I frequently choose
>> among
>>
>> x <- sample( 10 )
>> dxright <- c( 0, diff(x) )
>> dxleft <- c( diff(x), 0 )
>>
>> for calculation purposes depending on my needs.
>> --
>> Sent from my phone. Please excuse my brevity.
>>
>> On March 4, 2016 3:28:08 AM PST, Olivier Crouzet <
>> olivier.crouzet at univ-nantes.fr> wrote:
>> >Hi,
>> >
>> >(1) You should provide a minimal working example;
>> >
>> >(2) But anyway, does...
>> >
>> >x = sample(10)
>> >c(x[1],diff(x))
>> >
>> >... do what you want?
>> >
>> >Olivier.
>> >
>> >
>> >On Fri, 4 Mar 2016
>> >13:22:07 +0200 catalin roibu <catalinroibu at gmail.com> wrote:
>> >
>> >> Dear all!
>> >>
>> >> I want to calculate difference between successive values (cumulative
>> >> values) with R. I used diff function, but I want to keep the first
>> >> values.
>> >>
>> >> Please help me to solve this problem!
>> >>
>> >> Thank you!
>> >>
>> >> Best regards!
>> >>
>> >> CR
>> >>
>> >> --
>> >>
>> >> -
>> >> -
>> >> Catalin-Constantin ROIBU
>> >>
>> >> Lecturer PhD, Forestry engineer
>> >> Forestry Faculty of Suceava
>> >> Str. Universitatii no. 13, Suceava, 720229, Romania
>> >> office phone      +4 0230 52 29 78, ext. 531
>> >> mobile phone    +4 0745 53 18 01
>> >> FAX:                +4 0230 52 16 64
>> >> silvic.usv.ro <http://www.usv.ro/>
>> >>
>> >>      [[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.
>> >
>> >--
>> >  Olivier Crouzet, PhD
>> >  Laboratoire de Linguistique de Nantes -- UMR6310
>> >  CNRS / Université de Nantes
>> >  Chemin de la Censive du Tertre -- BP 81227
>> >  44312 Nantes cedex 3
>> >  France
>> >
>> >  http://www.lling.univ-nantes.fr/
>> >
>> >______________________________________________
>> >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.
>>
>>         [[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.
>
> --
>
> -
> -
> Catalin-Constantin ROIBU
>
> Lecturer PhD, Forestry engineer
>
> Forestry Faculty of Suceava
> Str. Universitatii no. 13, Suceava, 720229,
> office phone     +4 0230 52 29 78, ext. 531
> mobile phone   +4 0745 53 18 01
>                        +4 0766 71 76 58
> FAX:                +4 0230 52 16 64
> silvic.usv.ro <http://www.usv.ro/>
>
>         [[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.