Generic 'diff'

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

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