Issues with Kriging values #89
Description
I am performing an ordinary kriging and the results I get after performing the kriging are totally wrong. For simplicity, my grid points are also my data points. The working code is:
"Import libraries and modules"
import numpy as np
import gstools as gs
import tkinter as tk
from tkinter import filedialog
import pandas as pd
from scipy.spatial.distance import pdist, squareform
"Import data"
root = tk.Tk()
root.withdraw()
filepath = filedialog.askopenfilenames(parent=root, title='Choose a file')
data = pd.DataFrame()
for file in filepath:
df = pd.read_excel(file)
data = data.append(df)
data = data.iloc[:, :3]
data = data[~np.isnan(data).any(axis=1)]
data = np.array(data, dtype=np.float)
"Calculate semivariance"
sill = np.var(data[:, 2])
pwdist = squareform(pdist(data[:, :2]))
max_lag = np.int(np.ceil(np.max(pwdist)))
npoint = np.int(np.floor(max_lag/40))
firstlag = max_lag / 100
lags = np.linspace(firstlag, max_lag, npoint)
bin_center, gamma = gs.vario_estimate_unstructured((data[:,0], data[:,1]), data[:,2], lags)
"Fit theoretical variogram to data"
fit_model = gs.Stable(dim=2)
fit_model.set_arg_bounds(var=[0, sill])
fit_model.set_arg_bounds(len_scale=[0, 1000000])
fit_model.fit_variogram(bin_center, gamma, nugget=False)
ax = fit_model.plot(x_max=max_lag)
ax.plot(bin_center, gamma)
print(fit_model)
"Perform kriging"
OK = gs.krige.Ordinary(fit_model, [data[:, 0], data[:, 1]], data[:, 2])
OK.unstructured([data[:, 0], data[:, 1]])
ax = OK.plot()
ax.set_aspect("equal")
The semivariogram looks good (as attached below).
The value of my kriging should range between 0 and 400 as data[:, 2] ranges between this value. However, i am getting values between -3000 and 8000.
Find attached the data to reproduce the problem