[R] difference between successive values

[Jeff Newmiller]

"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
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>> silvic.usv.ro <http://www.usv.ro/>
>> 
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>> 
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>> 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.

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