The Bentley and Saxe paper answers the questions
(1) How can I draw a sample of n numbers in the range 0..1 such that
the numbers are returned in increasing order WITHOUT sorting and so
that all such sequences are equally likely in LINEAR time. That's the
code I showed in R.
(2) How can I do this
Is Peter's solution different then:
diffs <- cumsum(runif(9, 5, 100/9))
x <-runif(1,0,100-diffs[9])
c(x, x+diffs)
I ask because:
1. If yes, this is why more context is needed;
2. If no, the above avoids a sort.
Cheers,
Bert
On Tue, Jun 3, 2025 at 2:15 PM peter dalgaard wrote:
> Can't you j
Hi,
I dont see from the solution pov they are different.
One followup Q though, how can I extend this to draw only integer
mid-point between 0-100 while maintaining minimum difference as 5?
Also, are all generated points are equally likely?
Thanks for your time and suggestions.
Thanks and rega
Hi Peter,
Could you please help me to understand what is the basis of choosing
55 in runif(10,0,55))?
Thank you!
On Wed, 4 Jun 2025 at 02:45, peter dalgaard wrote:
>
> Can't you just generate 10 values in (0,55), sort them, generate the
> distances, add 5 and cumulate?
>
> > x <- sort(runif(10
Okay, I think I found the reason. This is due to accumulation of nine
5s in the cumsum. Thanks again for the elegant solution.
But I wonder, if the solution is simple then what is the significance
of the Research paper by Bentley and Saxe naming “Generating sorted
lists of random numbers” which Ri
Hi!
It's possible I'm wrong. But for me it looks like:
n_sample <- 300
v <- round(runif(n_sample, 0, 100), 2)
m <- matrix(v, ncol = 10)
m_s <- t(apply(m, 1, sort))
m_d <- t(apply(m_s, 1, diff))
m_5 <- m_d>=5
f <- rowSums(m_5) == 9
sum(f)
res <- m_s[f, ]
Regards,
Sergiy
On Wed, Jun 4, 2025 at 1
To answer my own question, yes they are different.
Peter's code can generate the solution 1 20 26 32 38 44 50 56 62 68. Mine
cannot.
So, again, context?
-- Bert
On Wed, Jun 4, 2025 at 4:43 AM Bert Gunter wrote:
> Is Peter's solution different then:
>
> diffs <- cumsum(runif(9, 5, 100/9))
> x
In Peter's solution, just sample without replacement from integers instead
of generating random uniforms. See ?sample.
-- Bert
On Wed, Jun 4, 2025 at 5:23 AM Brian Smith
wrote:
> Hi,
>
> I dont see from the solution pov they are different.
>
> One followup Q though, how can I extend this to dr
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