effective way to return only the first argument of "which()"

x <- runif(18e6)
system.time(for(i in 1:100)which(x>0.99)[1])

system.time(for(i in 1:100)which.max(x>0.99))

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of Jeff Newmiller
Sent: Wednesday, September 19, 2012 8:06 AM
To: Mike Spam; r-help at r-project.org
Subject: Re: [R] effective way to return only the first argument of "which()"

?which.max
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Mike Spam <ichmagspam at googlemail.com> wrote:

Hi,

I was looking for a function like "which()" but only returns the first
argument.
Compare:

x <- c(1,2,3,4,5,6)
y <- 4
which(x>y)

returns:
5,6

which(x>y)[1]
returns:
5

which(x>y)[1] is exactly what i need. I did use this but the dataset
is too big (~18 mio. Points).
That's why i need a more effective way to get the first element of a
vector which is bigger/smaller than a specific number.

I found "match()" but this function only works for equal numbers.



Thanks,
Nico