gstools.variogram.vario_estimate_axis¶
-
gstools.variogram.
vario_estimate_axis
(field, direction='x', estimator='matheron', no_data=nan)[source]¶ Estimates the variogram along array axis.
The indices of the given direction are used for the bins. Uniform spacings along the given axis are assumed.
The algorithm calculates following equation:
with being the bins.
Or if the estimator “cressie” was chosen:
with being the bins. The Cressie estimator is more robust to outliers [Webster2007].
- Parameters
field (
numpy.ndarray
ornumpy.ma.MaskedArray
) – the spatially distributed data (can be masked)direction (
str
orint
) – the axis over which the variogram will be estimated (x, y, z) or (0, 1, 2, …)estimator (
str
, optional) –the estimator function, possible choices:
”matheron”: the standard method of moments of Matheron
”cressie”: an estimator more robust to outliers
Default: “matheron”
no_data (
float
, optional) – Value to identify missing data in the given field. Default: numpy.nan
- Returns
the estimated variogram along the given direction.
- Return type
Warning
It is assumed that the field is defined on an equidistant Cartesian grid.
Notes
Internally uses double precision and also returns doubles.
References
- Webster2007
Webster, R. and Oliver, M. A. “Geostatistics for environmental scientists.”, John Wiley & Sons. (2007)