[R] intervals and data frames

[Sebastian Luque]

Hi,

I thought this would be close to what you wanted:

x <- seq(-1,1,.1)
y <- sample(x, 3)
r1 <- vector(mode = "numeric", length = length(x))
sapply(y, function(k) {
  y1 <- max(k - 0.1, -1)
  y2 <- min(k + 0.1, 1)
  r1[x >= y1 & x <= y2] <- 1
  r1
})

but found that it's not replacing 3 elements of r1 consistently. There
seems to be a problem with indexing in that last assignment. Can somebody
please explain why indexing by such a logical vector doesn't work here?


Regards,
Sebastian


Erin Hodgess <hodgess at gator.dt.uh.edu> wrote:
> Dear R people:
>
> I have a vector which runs from -1 to 1, by .1, inclusively.
>
> Easy to set up.  x <- seq(-1,1,.1)
>
> I then sample 3 numbers from x.
> y <- sample(x, 3)
>
> Suppose one of my values is -0.7.  I want to set up an interval
> around that
> y1 <- pmax(y-0.1,-1)
> y2 <- pmin(y+0.1,1)
> For the value -.7, the interval will run from -.8 to -.6.
> There will be several intervals.
>
> Again, nothing interesting so far.
>
> However, now I want to set up something that I will call
> r1.  Essentially, r1 "runs" between -1 and 1 as well.
> I want to place a value in r1 between -.8 and -.6 for my interval,
> and zeros elsewhere.
>
> I'm trying to use a data frame in which the first column represents
> the values from -1 to 1.  The remaining columns are initially set to
> zero.  Also, I'm trying to avoid loops.
>
> Any suggestions would be much appreciated.
>
> Thanks in advance,
> Sincerely
> Erin Hodgess
> Associate Professor
> Department of Computer and Mathematical Sciences
> University of Houston - Downtown
> mailto: hodgess at gator.uhd.edu
>
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-- 
Sebastian P. Luque