[R] Simulating mid-points from a defined range

[peter dalgaard]

Can't you just generate 10 values in (0,55), sort them, generate the distances, add 5 and cumulate? 

> x <- sort(runif(10,0,55))
> d <- diff(x)+5
> cumsum(c(x[1],d))
 [1] 12.27815 21.21060 26.37856 36.03812 41.97237 57.02945 67.86113
 [8] 75.74085 81.28533 98.30792


> On 3 Jun 2025, at 09.21, Brian Smith <briansmith199312 using gmail.com> wrote:
> 
> Hi Richard,
> 
> Thanks for your insight.
> 
> As I mentioned in one of my earlier emails to the group, I imposed a
> constraint of accuracy up to two decimal places in order to obtain a
> finite set of possible values. For instance, if I were to round values
> to zero decimal places, the number of unique sequences that could be
> generated would be strictly finite and quite limited. Therefore, I
> chose a precision of two decimal places to allow for a larger but
> still finite number of possibilities.
> 
> 
> Now, my question is: how can this accuracy constraint be imposed effectively?
> 
> Is the only practical method to generate samples, round each to two
> decimal places, and then check for duplicates to ensure uniqueness? If
> so, I’m concerned this might be inefficient, as many samples could be
> discarded, making the process time-consuming.
> 
> Is there a better or more efficient way to directly enforce this
> constraint while generating the values?
> 
> ________________________________
> 
> Additionally, could you please elaborate on your suggestion regarding
> imposing minimum gap constraints by subtracting and then adding back
> certain gaps?
> 
> 
> For example, based on your earlier guidance, one possible sequence I
> obtained is:
> 
> 
> 10.07181, 14.49839, 14.74435, 18.75167, 42.70361, 55.79623, 63.40264,
> 68.62261, 92.49899, 98.29308
> 
> 
> Now, I’d like to post-process this sequence to enforce a minimum
> difference constraint of, say, 5 units between values (including both
> lower and upper bounds).
> 
> What would be the appropriate way to modify the sequence to impose
> this kind of constraint?
> 
> 
> Many thanks for your time and insight.
> 
> On Tue, 3 Jun 2025 at 10:42, Richard O'Keefe <raoknz using gmail.com> wrote:
>> 
>> PS I forgot about the weird gaps requirement.
>> What you do is subtract the gaps off and then add them back.  I hope that is clear.
>> 
>> On Sun, 1 Jun 2025 at 6:52 AM, Brian Smith <briansmith199312 using gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> Let say I have a range [0, 100]
>>> 
>>> Now I need to simulate 1000 10 mid-points within the range with
>>> accuracy upto second decimal number.
>>> 
>>> Let say, one simulated set is
>>> 
>>> X1, X2, ..., X10
>>> 
>>> Ofcourrse
>>> 
>>> X1 < X2 < ... <X10
>>> 
>>> I have one more constraint that the difference between any 2
>>> consecutive mid-points shall be at-least 5.00.
>>> 
>>> I wonder if there is any Statistical theory available to support this
>>> kind of simulation.
>>> 
>>> Alternately, is there any way in R to implement this?
>>> 
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> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business SchoolSolbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
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