[R] find position to last number in a vector
apjaworski at mmm.com
apjaworski at mmm.com
Fri May 26 20:56:53 CEST 2006
I am sure there are several ways of doing this but how about something like
this:
y <- c(NA,NA,10,NA,2,NA,NA,1,NA,NA)
x <- c(10,20,30,40,50,60,70,80,85,100)
tail(x[!is.na(y)], 1)
or
rev(x[!is.na(y)])[1]
Rudimentary checks indicate that the second expression is much faster than
the first. Also, if y is contains NAs only, the first expression returns
numeric(0) and the second one NA.
Hope this helps,
Andy
__________________________________
Andy Jaworski
518-1-01
Process Laboratory
3M Corporate Research Laboratory
-----
E-mail: apjaworski at mmm.com
Tel: (651) 733-6092
Fax: (651) 736-3122
Anders
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[R] find position to last number in
a vector
05/26/2006 01:30
PM
Hello
Is there a function to extract the position (i.e. row number or more
desirable the value from another column with the same rownumber ) of
last number in a vector? This is done in a loop with 1000s of columns.
e.g.
vector/column.n: na,na,10,na,2,na,na,1,na,na
fixed column:10,20,30,40,50,60,70,80,85,100
result: 8 and/or 80
Thanks...
Best Regards
Anders
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