[R] diff in a dataframe

[Henrique Dallazuanna]

Perhaps you can do this:

cbind(df, sapply(rbind(c(NA, NA),log(df)), diff))

On 10/01/2008, Vishal Belsare <shoot.spam at gmail.com> wrote:
> I have a dataframe say:
>
> date   price_g   price_s
>          0.34        0.56
>          0.36        0.76
>            .              .
>            .              .
>            .              .
>
> and so on. say, 1000 rows.
>
> Is it possible to add two columns to this dataframe, by computing say
> diff(log(price_g) and diff(log(price_s)) ?
>
> The elements in the first row of these columns cannot be computed, but
> can I coerce this to happen and assign a missing value there? It would
> be really great if I could do that, because in this case I don't have
> to re-index my transformed series to the dates again in a new
> dataframe.
>
> Thanks in anticipation.
>
>
> Vishal Belsare
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O