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# Re: st: Gen Randomized geo coordinates within a range

 From Maarten Buis <[email protected]> To [email protected] Subject Re: st: Gen Randomized geo coordinates within a range Date Fri, 19 Aug 2011 13:52:43 +0200

```On Fri, Aug 19, 2011 at 12:36 PM, Maarten Buis <[email protected]> wrote:
> On Fri, Aug 19, 2011 at 11:17 AM,  <[email protected]> wrote:
>> I need to generate a set of random geographic coordinates (x,y) given
>> a central point, within a given range.
>
> Alternatively, if you want your range to be a circle with radius .5
> you can do so as below
<snip>

In the previous example the three draws had the same relative position
with respect to their centroid, below you will get not only different
centroids but also different relative positions.

*-------------- begin example --------------
clear
input x y
1 1
5 5
1 5
end

gen phi = .
gen r = .
forvalues i = 1/30 {
qui replace phi = 2*runiform()*_pi
qui replace r = .5*runiform()
gen xran`i' = r*cos(phi) + x
gen yran`i' = r*sin(phi) + y
local gr `"`gr' || scatter yran`i' xran`i'"'
}
scatter y x, aspect(1) `gr'
*-------------- end example -----------------
(For more on examples I sent to the Statalist see:
http://www.maartenbuis.nl/example_faq )

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------

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