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Re: st: Fuzzy matching (so to say) based on geographical coordinates
From
Nils Braakmann <[email protected]>
To
[email protected]
Subject
Re: st: Fuzzy matching (so to say) based on geographical coordinates
Date
Mon, 13 Jun 2011 15:29:59 +0100
Austin, Dimitriy, thanks for the quick response! That should get me going.
Cheers,
Nils
On Mon, Jun 13, 2011 at 3:11 PM, Austin Nichols <[email protected]> wrote:
> Nils Braakmann <[email protected]>:
> The simplest way, to my mind, is to do an unmatched merge and loop
> over observations, e.g.
> http://www.stata.com/statalist/archive/2009-09/msg00473.html
>
> On Mon, Jun 13, 2011 at 9:52 AM, Nils Braakmann
> <[email protected]> wrote:
>> Hi everyone,
>>
>> I have the following problem I would appreciate some help with: I have
>> two data files, one containing the location of certain events, the
>> other containing centroids of regions. Locations in both cases are
>> defined by latitude and longitude (lat and lon). What I aim to do is
>> to match each event to the nearest region, where the definition of
>> "nearest" is based on the ellipsoidal distance between the two
>> coordinates. The distances themselves could be computed using
>> -geodist-by Robert Picard.
>>
>> The coordinates in both data sets look like:
>> | lat lon |
>> |----------------------|
>> 1. | 55.22918 -161.9152 |
>> 2. | 52.24265 -175.1298 |
>> 3. | 61.17837 -149.1864 |
>> 4. | 60.93916 -160.1473 |
>> 5. | 58.74463 -156.9881 |
>>
>> I presume one way to proceed would be to compute all pairwise
>> distances between every event and every region and keep the respective
>> minimum. However, as I would expect problems such as mine to appear
>> rather frequently in fields such as geography, I wonder whether anyone
>> knows of a simpler way or of a program/ado-file (might be outside of
>> Stata) that could do the job. I basically try to avoid reinventing the
>> wheel for something that might be a fairly standard problem.
>>
>> Cheers,
>> Nils
>
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