On 2011-07-25 10:51, "Dénes TÓTH" wrote:

Hi,

you provided a character vector as an example. I guess you meant something
like:
x<- factor(c("1","2","3","4","<1"))

# You can identify those elements with an "<" by ?grep or ?grepl:
indices<- grep("<",as.character(x))

# You can transform those elements by ?as.numeric
as.numeric(x[indices])

I fail to see what this is supposed to accomplish. It gives

  as.numeric(x[indices])
  #[1] 1

Try changing x to

  x <- factor(c("1","2","3","4","<8"))

You'll still get

  as.numeric(x[indices])
  #[1] 1

?factor explains this.

Better just stick with a character vector to begin with.

Peter Ehlers


HTH,
   Denes


Hi all,

I'm trying to identify a particular digit or value within a vector of
factors. Specifically, this is environmental data where in some cases the
minimum value reported is "<" a particular number (and I want to
manipulate
only these). For example:

  x<-c("1","2","3","4","<1")

For a dataset that is hundreds or thousands of lines long, I'd like to
find
or identify only those that have a "<" symbol (R automatically stores the
entire vector in factor format due to these symbols when it imports the
data-I don't mind converting if necessary). Eventually, I'd like to divide
the number in half for these cases, but I think I have that coding lined
up
once I can just identify them from the stew.

I've exhausted help and net resources so far...

Thanks,
Ryan


--

Ryan Utz, Ph.D.
Aquatic Ecologist/STREON Scientist
National Ecological Observatory Network

Home/Cell: (724) 272-7769
Work: (720) 746-4844 ext. 2488

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