[R] string-to-number

[Marc Schwartz]

On Sat, 2006-08-19 at 07:58 -0400, Charles Annis, P.E. wrote:
> 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?
> 
> Thank you.

One more step:

> as.numeric(unlist(strsplit(repeated.measures.columns, ",")))
[1]  3  6 10

Use unlist() to take the output of strsplit() and convert it to a
vector, before coercing to numeric.

HTH,

Marc Schwartz