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# st: Re: st: Identify Neighbor Regions with Latitudes and Longitudes‏

 From Robert Picard To "statalist@hsphsun2.harvard.edu" Subject st: Re: st: Identify Neighbor Regions with Latitudes and Longitudes‏ Date Sun, 23 Sep 2012 13:23:22 -0500

```It all depends on what you mean by adjacent neighbors. You can use
-geodist-, available on SSC to calculate distances using lat/lon
pairs. You can use -geonear-, also available from SSC to identify all
neighbors within a certain distance (say 20 miles) or to find say the
nearest 5 cities. If you mean adjacent according to some geopolitical
boundaries, then you would need shapefiles that describe those
boundaries. If you mean adjacent in geometric sense, then you will
need to draw the Voronoi (Thiessen) polygons around each city. I don't
know of any Stata tools to do that. You can try to approximate the
polygons using an array of points arranged in a grid.

On Sep 23, 2012, at 10:52 AM, "曦 田" <txsnowsea@hotmail.com> wrote:

>
> Hello, Brendan,
>
> Thanks a lot for replaying. With distance matrix, I am not quite understand how to figure up which cities are the neighbor cities for a particular cities. Are you talking about the nearest city? I need all the adjoining cities for each one. Some of my friends suggest me to read the map. Map maybe helpful when I look at the state levels, but not city levels. With 300 cities, the job is just huge.
>
>
> Xi
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>> From: brendan.halpin@ul.ie
>> To: statalist@hsphsun2.harvard.edu
>> Subject: Re: st: Identify Neighbor Regions with Latitudes and Longitudes‏
>> Date: Sun, 23 Sep 2012 10:50:29 +0100
>>
>> On Sat, Sep 22 2012, � � wrote:
>>
>>> Is it possible to identify all neighboring cities, NOT the nearest
>>> cities with just latitudes and longitudes?
>>
>> You need to convert lat/lon pairs to distances: there is an interesting
>> summary of the various ways of doing this at
>> http://www.movable-type.co.uk/scripts/latlong.html. What is referred to
>> there as the equirectangular projection is probably accurate enough.
>>
>> But first you need to make a data-set of city-pairs. That seems to be a
>> job for the -joinby- command.
>>
>> Brendan
>> --
>> Brendan Halpin, Department of Sociology, University of Limerick, Ireland
>> Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F1-009 x 3147
>> mailto:brendan.halpin@ul.ie ULSociology on Facebook: http://on.fb.me/fjIK9t
>>
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>
>
> *
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```