>> recycle(x, y, z);
>>
>> Hadley
>
>
> In a way, we can already use sugar rep_len.
>
> rep_len( x, 30 )
>
> will recycle x into a vector of length 30, lazily.
Agreed, but a helper function would automate this process:
int length = max(x.length(), y.length(), z.length())
# check integer multiples
Le 18/11/12 16:12, Hadley Wickham a écrit :
microbenchmark(
pdist1(0.5, ys),
pdist2(0.5, ys),
pdist3(0.5, ys)
)
# 10-fold slower?? Maybe it's because I'm using a double instead of
# a numeric vector?
That's weird. Not sure where the ineffiency is. Some hunting.
My guess is that sug
>> microbenchmark(
>>pdist1(0.5, ys),
>>pdist2(0.5, ys),
>>pdist3(0.5, ys)
>> )
>> # 10-fold slower?? Maybe it's because I'm using a double instead of
>> # a numeric vector?
>
> That's weird. Not sure where the ineffiency is. Some hunting.
> My guess is that sugar pow needs a refresh.
Another, with mapply. But there we have to use rep since our mapply only
works on vector expressions.
inline double distance(double y, double x){ return pow( (y-x), 2.0 ) ; }
// [[Rcpp::export]]
NumericVector pdist6(double x, NumericVector ys) {
return mapply( ys, rep(x,ys.size()), distance
Hi,
While there, consider this version based on sapply:
class Distance {
public:
typedef double result_type ;
Distance( double x_ ) : x(x_){}
inline double operator()(double y) const { return pow( (y-x), 2.0 ) ; }
private:
double x;
} ;
// [[Rcpp::export]]
NumericVector pdist
Le 17/11/12 14:42, Hadley Wickham a écrit :
Hi all,
I've included what seems to be a simple application of Rcpp sugar
below, but I'm getting some very strange results. Any help would be
much appreciate!
Thanks,
Hadley
library(Rcpp)
library(microbenchmark)
# Compute distance between single p
Hi all,
I've included what seems to be a simple application of Rcpp sugar
below, but I'm getting some very strange results. Any help would be
much appreciate!
Thanks,
Hadley
library(Rcpp)
library(microbenchmark)
# Compute distance between single point and vector of points
pdist1 <- function(x
