[R-sig-Geo] Randomly moving a locality (within set limits)

[Barry Rowlingson]

On Mon, Aug 25, 2014 at 11:03 AM, Alastair Potts <potts.a at gmail.com> wrote:
> Dear Frede, Barry and Don,
>
> Thanks very for your thoughts!
>
> Frede's function looks perfect! Thanks very much!!!
>
> Barry, would not setting random U(-N,N) distance deal with the uniform
> distance problem [i.e. distance <- runif(1,-15,15)].
>

 No, that would just be the same!

Its all explained here:

http://mathworld.wolfram.com/DiskPointPicking.html

>
>
> On 25 August 2014 10:48, Barry Rowlingson <b.rowlingson at lancaster.ac.uk>
> wrote:
>>
>> > Now choose
>> >
>> > bearing <- runif(1, 0, 360)
>> >
>> > and
>> >
>> > distance <- runif(1, 0, 15)
>> >
>> > Please check the formulas against the homepage above.
>>
>>  Note: choosing a random bearing U(0,360) and a random U(0,N) distance
>>  DOESNT generate a uniform distribution over the disk of radius N!
>> You get more points near the centre!
>>
>>  Barry
>
>
>
>
> --
> Dr. Alastair J. Potts
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