[R-sig-Geo] Solution in R for finding closest points:

[Don MacQueen]

Mary,

You might also want to look at the nncross function in the spatstat package.

-Don

At 8:58 AM -0700 3/18/08, Rick Reeves wrote:
>Mary:
>
>Have a look at this tutorial:
>
>http://nceas.ucsb.edu/scicomp/GISSeminar/UseCases/AssignClosestPointsR/AssignClosestPointsR.html
>
>Uses R, which has a good set of geospatial analysis functions. This 
>web site has several other examples!
>
>Hope this helps,
>Rick Reeves
>
>Mary.Barnes at csiro.au wrote:
>>Hi all,
>>I recently joined, and have a rather basic question. I'd appreciate any
>>help to find some R routines to find the closest match to GIS
>>coordinates. I suspect simply using the Euclidean distance. I could
>>write some code but I suspect there is some already.  I describe three
>>classes of difficulties below. 1. Sometimes there are simple 
>>measurement error differences in GIS from
>>vine coordinates measurement at different times. This may also relate to
>>ability to get close to trunk in addition to equipment measurement
>>error.
>>2. Sometimes we encounter the problem of matching aerial spatial records
>>with vines. Aerial and satellite imagery is on a different scales
>>(pixels) to vine spacing. But we would like to be able to match these as
>>best we can.
>>3. Sometimes we want to match kriged clusters to target vine GPS
>>coordinates.
>>
>>Typically I have 100 target vines at each of 5 vineyards.
>>
>>Euclidean distance  approx. = square root of  ( differences between
>>Eastings squared plus the differences between Northings squared)
>>
>>Any help will be appreciated  Mary Barnes
>>
>>	[[alternative HTML version deleted]]
>>
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>
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062