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

[Rick Reeves]

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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