On Wed, Aug 5, 2009 at 11:28 PM, Erik Iverson <eiverson@nmdp.org> wrote:

> First, this has nothing to do with "0".  Assigning 1000 to an element of v
> would also have this effect.  Two, the first element of a vector is indexed
> by "1", not "0".  While what you wrote isn't a syntax error (v[0] <- 0), it
> may be not doing what you think, but I don't know.


According to R Language Definition, foo[0] always returns an empty vector.
No idea why this is useful but it is a bit confusing that one can actually
assign to foo[0] (and even foo[NULL] ) with some effect:

foo <- 1:10
class(foo)  # integer
foo[NULL] <- "une souris verte"
foo     # all the same numbers there
class(foo)  # changed to character!!

k


>
> Finally, the answer to your question.  Try typing class(0)  to see that it
> is in fact numeric.
>
> So you may want v[1] <- as.integer(0) to get what you are expecting.
>
> HTH.
>
> -----Original Message-----
> From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org]
> On Behalf Of Steve Jaffe
> Sent: Wednesday, August 05, 2009 3:16 PM
> To: r-help@r-project.org
> Subject: [R] why is 0 not an integer?
>
>
> Why when I assign 0 to an element of an integer vector does the type change
> to numeric?
> Here is a particularly perplexing example:
> > v <- 0:10
> > v
>  [1]  0  1  2  3  4  5  6  7  8  9 10
> > class(v)
> [1] "integer"
> > v[0] <- 0
> > class(v)
> [1] "numeric"  #!!
> >
>
> --
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>
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