R help - May 2009 - Generic 'diff'

I would like to apply a function 'f' to the lagged version of a vector
and
the vector itself.

This is easy to do explicitly:

      mapply( f, v[-1], v[-length(v)] )

or in the case of a pointwise vector function, simply

      f( v[-1], v[-length(v)] )

This is essentially the same as 'diff' but with an arbitrary function,
not
'-'.

Is there a standard way to do this? Is there any particular reason that
'diff' should not have an 'f' argument?

            -s

	[[alternative HTML version deleted]]

You can define a new class for the object diff operates
on and then define your own diff method for that. For
some examples see:

methods(diff)



On Mon, May 18, 2009 at 4:24 PM, Stavros Macrakis <macrakis at
alum.mit.edu> wrote:
> I would like to apply a function 'f' to the lagged version of a
vector and
> the vector itself.
>
> This is easy to do explicitly:
>
> ? ? ?mapply( f, v[-1], v[-length(v)] )
>
> or in the case of a pointwise vector function, simply
>
> ? ? ?f( v[-1], v[-length(v)] )
>
> This is essentially the same as 'diff' but with an arbitrary
function, not
> '-'.
>
> Is there a standard way to do this? Is there any particular reason that
> 'diff' should not have an 'f' argument?
>
> ? ? ? ? ? ?-s
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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