[R-sig-Geo] How to deal with data points having the same lat long position?

[José Luis Rotundo]

Dear list,

I am working with a database of farm yields across USA and the objective is
to map soybean yields. To preserve the identity of the farmers, they only
provided the zipcode of the farm. Then I attached the zip code lat and
long. The problem I have is that several farms belongs to the same zipcode
and therefore they have the same lat and long. Having this repeated
locations troubles the construction of the variogram.

Option (A) was to average these values, but I loss almost 4000 data points
out of 15000.

Option (B) would be to slightly modify the lat and long values.

My questions:

1. Does anyone knows a way to efficiently detect and slightly  modify the
repeated lat and long values?.
2. Is there any other way to deal with repeated values when doing variograms
?

any help will be appreciated.

Best,

Jose



-- 


José L. Rotundo
CONICET
Facultad de Ciencias Agrarias
Univ. Nacional de Rosario
Zavalla, Santa Fe
Argentina

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