Re: [R] string-to-number

From: Peter Dalgaard <p.dalgaard_at_biostat.ku.dk>
Date: Sat 19 Aug 2006 - 22:12:13 EST

"Charles Annis, P.E." <Charles.Annis@statisticalengineering.com> writes:

> Greetings, Amigos:
>
> I have been trying without success to convert a character string,
> > repeated.measures.columns
> [1] "3,6,10"
>
> into c(3,6,10) for subsequent use.
>
> as.numeric(repeated.measures.columns) doesn't work (likely because of the
> commas)
> [1] NA
> Warning message:
> NAs introduced by coercion
>
> I've tried many things including
> strsplit(repeated.measures.columns, split = ",")
>
> which produces a list with only one element, viz:
> [[1]]
> [1] "3" "6" "10"
>
> as.numeric() doesn't like that either.
>
> Clearly: 1) I cannot be the first person to attempt this, and 2) I've made
> this WAY harder than it is.
>
> Would some kind soul please instruct me (and perhaps subsequent searchers)
> how to convert the elements of a string into numbers?

3) you're almost there, just not realizing it:

> x <- "3,6,10"
> as.numeric(strsplit(x,split = ",")[[1]])
[1] 3 6 10

or for that matter

> scan(textConnection(x), sep=",")
Read 3 items
[1] 3 6 10

although that leaves you with a dangling open connection.

-- 
   O__  ---- Peter Dalgaard             ุster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

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Received on Sat Aug 19 22:21:12 2006

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