Message-ID: <971536df0905181500g7645a6f3k58302e58bddfc247@mail.gmail.com>
Date: 2009-05-18T22:00:23Z
From: Gabor Grothendieck
Subject: Generic 'diff'
In-Reply-To: <8b356f880905181448q76a58fa3o2496dc2e57cdfc47@mail.gmail.com>
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]]
>> >
>> > ______________________________________________
>> > R-help at r-project.org mailing list
>> > 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.
>> >
>
>