R help - Dec 2009 - find the index of the next largest element in a sorted vector

Hi,

How can I find the index of the next largest element in a sorted vector if
an element is not found.

for example, searching 2 in c(0,3,4) would return 1 since 2 is not in the
vector and 0 is the next largest element to 2.

I tried which and match and neither returns such information.
> which(c(0,3,4) == 2)
integer(0)
> match(2, c(0,3,4))
[1] NA


thanks

Jeff

On Dec 2, 2009, at 9:34 AM, Hao Cen wrote:
> Hi,
>
> How can I find the index of the next largest element in a sorted  
> vector if
> an element is not found.
>
> for example, searching 2 in c(0,3,4) would return 1 since 2 is not  
> in the
> vector and 0 is the next largest element to 2.
>
> I tried which and match and neither returns such information.
>
>> which(c(0,3,4) == 2)
> integer(0)
>> match(2, c(0,3,4))
> [1] NA
Take a look at these. I changed to problem so that the "answer would  
be in the middle of the sequence.

 > which(c(0,3,4) <= 2)
[1] 1   # but which would have retruned several values if the match  
were in the middle
 > which(c(-3,-1, 0,3,4) <= 2)
[1] 1 2 3
 > tail(which(c(-3,-1,0,3,4) <= 2),1)
[1] 3  # the desired index

--

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

Is this what you want:
> x <- c(0,3,4)
> ?findInterval
> findInterval(2, x)
[1] 1
>

On Wed, Dec 2, 2009 at 9:34 AM, Hao Cen <hcen at andrew.cmu.edu>
wrote:
> Hi,
>
> How can I find the index of the next largest element in a sorted vector if
> an element is not found.
>
> for example, searching 2 in c(0,3,4) would return 1 since 2 is not in the
> vector and 0 is the next largest element to 2.
>
> I tried which and match and neither returns such information.
>
>> which(c(0,3,4) == 2)
> integer(0)
>> match(2, c(0,3,4))
> [1] NA
>
>
> thanks
>
> Jeff
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?