Note that this could be done like this for ordinary
vectors:
> x <- seq(1:4)^2
> apply(embed(x, 2), 1, function(x, f) f(rev(x)), f = diff)
[1] 3 5 7
> apply(embed(x, 2), 1, function(x, f) f(rev(x)), f = sum)
[1] 5 13 25
or a method to rollapply in zoo could be added for ordinary vectors.
Here i
Wacek Kusnierczyk wrote:
>
> btw., the error message here is confusing:
>
> lag = 1:2
> diff(1:10, lag=lag)
> # Error in diff.default(1:10, lag = lag) :
> # 'lag' and 'differences' must be integers >= 1
>
> is.integer(lag)
> # TRUE
> all(lag >= 1)
> # TRUE
>
> wh
Wacek Kusnierczyk wrote:
> Stavros Macrakis wrote:
>
>>
[...]
>> I am not talking about creating a new class with an analogue to the
>> subtraction function. I am talking about a function which applies another
>> function to a sequence and its lagged version.
>>
>> Functional arguments are use
Stavros Macrakis wrote:
> On Mon, May 18, 2009 at 6:00 PM, Gabor Grothendieck
>> wrote:
>>
>
>
>> 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.
>>
>>
>
> I am not talking about creating a new class with an analogue
On Mon, May 18, 2009 at 6:00 PM, Gabor Grothendieck wrote:
> 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.
>
I am not talking about creating a new class with an analogue to the
subtraction function. I am talking about a function
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 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
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
replac
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 wrote:
> I would like to apply a function 'f' to the lagged version of a vector and
> the vector itse
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
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