[R] Finding/identifying a value within a factor

["Dénes TÓTH"]

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])

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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