Displaying 2 results from an estimated 2 matches for "fastsolution".
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2011 Apr 15
1
[Rcpp-devel] Find number of elements less than some number: Elegant/fastsolution needed
On Thu, Apr 14, 2011 at 7:02 PM,
<rcpp-devel-request at r-forge.wu-wien.ac.at> wrote:
> I was able to write a very short C++ function using the Rcpp package
> that provided about a 1000-fold increase in speed relative to the best
> I could do in R. ?I don't have the script on this computer so I will
> post it tomorrow when I am back on the computer at the office.
>
>
2011 Apr 14
3
Find number of elements less than some number: Elegant/fast solution needed
Take vector x and a subset y:
x=1:10
y=c(4,5,7,9)
For each value in 'x', I want to know how many elements in 'y' are less than 'x'.
An example would be:
sapply(x,FUN=function(i) {length(which(y<i))})
[1] 0 0 0 0 1 2 2 3 3 4
But this solution is far too slow when x and y have lengths in the millions.
I'm certain an elegant (and computationally efficient)