How about clip():
p = clip(p, 0.0, 1.0);
Great idea!!!
On Wed, Nov 21, 2012 at 2:00 PM, Romain Francois
<rom...@r-enthusiasts.com>wrote:
> Le 21/11/12 13:22, Darren Cook a écrit :
>
> I wrote:
>>
>>> P.S. I don't think the sugar versions can be made any quicker, because
>>>>> they have to allocate intermediate vectors, and do more memory copies.
>>>>>
>>>>
>> By "sugar versions" I meant vacc4() vs. vacc3()
>> (https://gist.github.com/**4111256 <https://gist.github.com/4111256>)
>> not pmin() and friends. The vacc4()
>> code looks like:
>>
>> NumericVector p(age.size());
>> p = 0.25 + 0.3 * 1 / (1 - exp(0.04 * age)) + 0.1 * ily;
>> p = p * ifelse(female, 1.25, 0.75);
>> p = pmax(0,p);
>> p = pmin(1,p);
>>
>> Each operation copies the whole NumericVector each time, each of which
>> needs a memory allocation.
>>
>
> Nope. The NumericVector::operator=( sugar expression ) is used and memory
> for p is allocated just once, when p is constructed with this lne:
>
> NumericVector p(age.size());
>
> None of the "p = ..." lines allocate memory for p.
>
> The differences in timing don't come from additional memory allocations.
>
> Although this thread allows me to identify something that can be improved
> in the operator=.
>
>
> vacc3a() does the same pipeline of operations on a single double, which
>> is therefore likely to be a single CPU register, and the whole of
>> vacc3a() will be inlined in vacc3().
>>
>>
>> Also, I'm probably goinf to add a function that does the equivalent of :
>>>
>>> pmax( b, pmin( a, x ) )
>>>
>>> I'm thinking of naming it pminmax. Any better idea ?
>>>
>>
>> I'd expect a function called minmax() to return two values, the min and
>> max function. The "p" prefix is too subtle for me :-)
>>
>> How about clip():
>> p = clip(p, 0.0, 1.0);
>>
>
>
> I like "clip".
>
>
>
> This is such a common operation that I'm surprised R doesn't already
>> have a function like this!
>>
>> Darren
>>
>>
>>
>
> --
> Romain Francois
> Professional R Enthusiast
> +33(0) 6 28 91 30 30
>
> R Graph Gallery:
> http://gallery.r-enthusiasts.**com<http://gallery.r-enthusiasts.com>
> `- http://bit.ly/SweN1Z : SuperStorm Sandy
>
> blog:
> http://romainfrancois.blog.**free.fr<http://romainfrancois.blog.free.fr>
> |- http://bit.ly/RE6sYH : OOP with Rcpp modules
> `- http://bit.ly/Thw7IK : Rcpp modules more flexible
>
> ______________________________**_________________
> Rcpp-devel mailing list
> Rcpp-devel@lists.r-forge.r-**project.org<Rcpp-devel@lists.r-forge.r-project.org>
> https://lists.r-forge.r-**project.org/cgi-bin/mailman/**
> listinfo/rcpp-devel<https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel>
>
_______________________________________________
Rcpp-devel mailing list
Rcpp-devel@lists.r-forge.r-project.org
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
