> On 15 Dec 2016, at 13:34, Brijesh Mishra <brijeshkmis...@gmail.com> wrote:
>
> Dear Mr Hasselman,
>
> I missed you mail, while I was typing my own mail as a reply to Mr.
> Barradas suggestion. In fact, I implemented your suggestion even
> before reading it. But, I have a concern that I have noted (though its
> only hypothetical- such a scenario is very unlikely to occur). Is
> there a way to restrict such calculations co_code1 wise?
Like this?
df2 <- ddply(df1,"co_code1", transform,
growth=c(NA, ifelse(diff(fyear1)==1, (exp(diff(log(sales1)))-1)*100,NA))
)
But do also look at Petr Pikal's solution. Which of the two solutions you
prefer depends on what you want in your special case.
Berend
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