[R] Generic 'diff'

[Gabor Grothendieck]

I understood what you were asking but R is an oo language so
that's the model to use to do this sort of thing.

On Mon, May 18, 2009 at 5:48 PM, Stavros Macrakis <macrakis at alum.mit.edu> wrote:
> I guess I wasn't very clear.  The goal is not to define diff on a different
> object type, but to have a different 'subtraction' operator with the same
> lag logic.  An easy example would be quotient instead of subtraction. Of
> course I could do that by simply cutting and pasting diff.default and
> replacing '-'(a,b) with f(a,b), but it's cleaner to use a standard function
> if there is one.
>
>           -s
>
> On Mon, May 18, 2009 at 5:05 PM, Gabor Grothendieck
> <ggrothendieck at gmail.com> wrote:
>>
>> 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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>> >
>
>