Variogram estimation without spatial reference

Am 12.06.2012 17:29, schrieb Gunnar Oehmichen:

Dear R-Sig-Geo list,

as part of an applied field-laboratory course, I will try to estimate
variograms of soil-lipid contents for two meadows differing in use.

Samples were taken in the following scheme:

Code dist X Y Wat mead Pair
21 B6-1 0.0 443840 5451412 B B6 6
22 B6-1 0.5 443841 5451410 B B6 6
23 B6-1 1.0 443843 5451410 B B6 6
24 B6-1 2.0 443844 5451411 B B6 6
25 B6-1 4.0 443841 5451410 B B6 6
26 B6-1 8.0 443848 5451409 B B6 6
...

column dist represents the distance [m] to the preceding point.

This scheme was replicated on each meadow 5 times to facilitate
replicates of each lag (0.5, 1.0, 2.0, 4.0, 8.0). We picked a random
point (dist = 0.0) sampled, moved a distance of 0.5 m in a random
direction, sampled and repeated the procedure with increasing distances.
Allthough lattitude and longitude were recorded (X and Y), I do not
consider these values to be helpful, since the measurement error of the
GPS device is ~ 6m, so a much coarser resolution than needed.

Results of the analysis are still missing, so no need to worry about
that.

but to the point, do you know of a way to use functions like variogram()
with this kind of data?

No, but it should be pretty easy to implement a function that calculates
semivariance between the rows of your data (using diff()). Taking the
average of semivariances for each value of dist gives you a
semivariogram. But it gives you not more than 10 point pairs for each
distance, which is not much.

HTH,
Tom

Thanks a lot,

Gunnar Oehmichen