Haven't seen a solution using ave...
d$diff <- ave( d$num, d$year, FUN = function( v ) { v - v[ 1 ] } )
--
Sent from my phone. Please excuse my brevity.
On October 28, 2016 12:46:15 PM CDT, William Dunlap via R-help
<r-help@r-project.org> wrote:
>You could use match() to find, for each row, the index of the first
>row with the give row's year:
>
>> d <- data.frame(year=c(rep(2001, 3), rep(2002, 3)),
> num=c(25,75,150,30,85,95))
>> indexOfFirstOfYear <- with(d, match(year, year))
>> indexOfFirstOfYear
>[1] 1 1 1 4 4 4
>> d$diff <- d$num - d$num[indexOfFirstOfYear]
>> d
> year num diff
>1 2001 25 0
>2 2001 75 50
>3 2001 150 125
>4 2002 30 0
>5 2002 85 55
>6 2002 95 65
>
>
>Bill Dunlap
>TIBCO Software
>wdunlap tibco.com
>
>On Thu, Oct 27, 2016 at 9:20 PM, Ashta <sewa...@gmail.com> wrote:
>
>> Hi all,
>>
>> I want to calculate the difference between successive row values to
>> the first row value within year.
>> How do I get that?
>>
>> Here is the sample of data
>> Year Num
>> 2001 25
>> 2001 75
>> 2001 150
>> 2002 30
>> 2002 85
>> 2002 95
>>
>> Desired output
>> Year Num diff
>> 2001 25 0
>> 2001 75 50
>> 2001 150 125
>> 2002 30 0
>> 2002 85 55
>> 2002 95 65
>>
>> Thank you.
>>
>> ______________________________________________
>> R-help@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.
>>
>
> [[alternative HTML version deleted]]
>
>______________________________________________
>R-help@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.
______________________________________________
R-help@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.
