[R] Creating a new vector

[Gabor Grothendieck]

Here are 3 possibilities:

y <- seq(-3, 3) # test data

ifelse(y < 0, y, NA)

replace(y, y >= 0, NA)

z <- y
z[y >= 0] <- NA

On 11/20/06, Amir Safari <amsa36060 at yahoo.com> wrote:
>
>
>
>     Dear R Users,
>
>  Suppose we want to creat a new vector ( x ) from a current vector (y)  of length 1000. The current vector y includes negative, zero and  positive values. We want our new vector x includes the negative values  in y, otherwise NA with the same length as y.
>
>  For this, we have  x=y[y<0]  . Now x includes a subset of  y with shorter length than y. With x=match(y,x) we would have  a  vector of indices equal to the length of y. x=y[x] gives us a vector of  values with the same length as y. But when I implement such a  procedure, x dose not merely include negative values. It includes  negative, NA and also positive values.
>  What could be the reason for appearing pasitive values? And how to  correct this? And more generally how can this purpose be coded more  convenient?
>
>  Thank you so much for any reply.
>
>  Amir Safari
>
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