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Exercise

Variogram estimation

You can use the gstat package to plot variogram clouds and the variograms from data. Recall:

  • The variogram cloud shows the differences of the measurements against distance for all pairs of data points.
  • The binned variogram divides the cloud into distance bins and computes the average difference within each bin.

The y-range of the binned variogram is always much smaller than the variogram cloud because the cloud includes the full range of values that go into computing the mean for the binned variogram.

Instructions
100 XP

The acidity survey data, ca_geo and the missing value index, miss have been pre-defined.

  • The gstat variogram() function uses the cloud argument to plot a variogram cloud. Use the miss vector from the previous exercise to select non-missing data.
  • The data is in meters, so use a 10km cutoff to prevent the cloud being too dense.
  • Plot a binned variogram of the non-missing data - the default cloud parameter is FALSE.
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