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name: scikit-gstat description: | Geostatistical analysis with scikit-learn style API. Compute variograms, kriging interpolation, and spatial correlation analysis. Use when Claude needs to: (1) Compute experimental variograms from spatial data, (2) Fit variogram models (spherical, exponential, gaussian, matern), (3) Perform Ordinary or Universal Kriging interpolation, (4) Assess spatial anisotropy with directional variograms, (5) Cross-validate spatial models, (6) Analyze spatio-temporal data, (7) Export variogram parameters for other geostatistical software.

SciKit-GStat - Geostatistics

Quick Reference

import skgstat as skg
import numpy as np

# Create variogram
V = skg.Variogram(coordinates=coords, values=values, n_lags=15)

# Fit model
V.model = 'spherical'
print(f"Range: {V.parameters[0]:.2f}, Sill: {V.parameters[1]:.2f}")

# Kriging interpolation
ok = skg.OrdinaryKriging(V)
predictions = ok.transform(grid_coords)

Key Classes

Class	Purpose
Variogram	Empirical and theoretical variograms
OrdinaryKriging	Interpolation with spatial correlation
DirectionalVariogram	Anisotropic variograms
SpaceTimeVariogram	Spatio-temporal analysis

Essential Operations

Create and Fit Variogram

import skgstat as skg

V = skg.Variogram(
    coordinates=coords,      # (n, 2) array of x, y
    values=values,           # (n,) array of measurements
    n_lags=15,
    maxlag='median'          # or specific distance
)

# Fit model: 'spherical', 'exponential', 'gaussian', 'matern', 'stable'
V.model = 'spherical'

# Get parameters
print(f"Range: {V.parameters[0]:.2f}")
print(f"Sill: {V.parameters[1]:.2f}")
print(f"Nugget: {V.parameters[2]:.2f}")
print(f"RMSE: {V.rmse:.4f}")

Ordinary Kriging

import skgstat as skg
import numpy as np

V = skg.Variogram(coords, values, model='spherical')
ok = skg.OrdinaryKriging(V)

# Create prediction grid
x = np.linspace(0, 100, 50)
y = np.linspace(0, 100, 50)
xx, yy = np.meshgrid(x, y)
grid_coords = np.column_stack([xx.ravel(), yy.ravel()])

# Predict
predictions = ok.transform(grid_coords)
Z = predictions.reshape(xx.shape)

# Get variance
ok.return_variance = True
predictions, variance = ok.transform(grid_coords)

Directional Variogram

import skgstat as skg

DV = skg.DirectionalVariogram(
    coordinates=coords,
    values=values,
    azimuth=45,          # Direction in degrees
    tolerance=22.5,      # Angular tolerance
    bandwidth='q33'      # Perpendicular bandwidth
)

# Check anisotropy
for az in [0, 45, 90, 135]:
    DV.azimuth = az
    print(f"Azimuth {az}: Range = {DV.parameters[0]:.2f}")

Cross-Validation

import skgstat as skg
from sklearn.model_selection import cross_val_score

V = skg.Variogram(coords, values, model='spherical')
ok = skg.OrdinaryKriging(V)

scores = cross_val_score(ok, coords, values, cv=5, scoring='neg_mean_squared_error')
print(f"CV RMSE: {np.sqrt(-scores.mean()):.4f}")

Robust Estimators

import skgstat as skg

# Use robust estimator for noisy data
V = skg.Variogram(
    coords, values,
    estimator='cressie'  # 'matheron', 'cressie', 'dowd', 'genton'
)

Quick Model Reference

Model	Behavior
spherical	Most common, linear near origin
exponential	Never reaches sill, gradual approach
gaussian	Parabolic near origin, smooth
matern	Flexible smoothness control

Tips

1. Maxlag should be ~50% of study area diagonal
2. Use robust estimators (cressie, dowd) with noisy data
3. Test multiple models and compare RMSE
4. Check anisotropy with directional variograms before kriging

References

• Variogram Models - Model equations and parameters
• Kriging Methods - Kriging types and configuration

Scripts

• scripts/variogram_analysis.py - Complete variogram analysis workflow