Last week I asked a question about finding a way to interpolate a surface from multiple curves (data from multiple Excel files) and someone referred me to a question which explains how to use scipy.interpolate.RBFInterpolator (How can I perform two-dimensional interpolation using scipy?).
I tried this method but I am getting a bad surface fitting (see the pictures below). Does anyone understand what is wrong with my code? I tried to change the kernel parameter but "linear" seems to be the best. Am I doing an error when I am using np.meshgrid? Thanks for the help.
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import os
from scipy.interpolate import RBFInterpolator
fig = plt.figure(figsize=(15,10),dpi=400)
ax = fig.gca(projection='3d')
# List all the results files in the folder (here 'Sress_Strain') to plot them.
results_list = os.listdir(r"C:/Users/bdhugu/Desktop/Strain_Stress")
for i in range(len(results_list)):
if i == 0:
results = pd.read_excel(r"C:/Users/bdhugu/Desktop/Strain_Stress/"+results_list[i])
strain = results["Strain (mm/mm)"]
stress = results["Stress (MPa)"]
strain_rate = results["Strain rate (s^-1)"]
if i>0:
new_results = pd.read_excel(r"C:/Users/bdhugu/Desktop/Strain_Stress/"+results_list[i])
new_strain = new_results["Strain (mm/mm)"]
new_stress = new_results["Stress (MPa)"]
new_strain_rate = new_results["Strain rate (s^-1)"]
strain = strain.append(new_strain, ignore_index=False)
stress = stress.append(new_stress, ignore_index=False)
strain_rate = strain_rate.append(new_strain_rate,ignore_index=False)
# RBFINTERPOLATOR METHOD
# ----------------------------------------------------------------------------
x_scattered = strain
y_scattered = strain_rate
z_scattered = stress
scattered_points = np.stack([x_scattered.ravel(), y_scattered.ravel()],-1)
x_dense, y_dense = np.meshgrid(np.linspace(min(strain), max(strain), 20),np.linspace(min(strain_rate), max(strain_rate), 21))
dense_points = np.stack([x_dense.ravel(), y_dense.ravel()], -1)
interpolation = RBFInterpolator(scattered_points, z_scattered.ravel(), smoothing = 0, kernel='linear',epsilon=1, degree=0)
z_dense = interpolation(dense_points).reshape(x_dense.shape)
fig = plt.figure(figsize=(15,10),dpi=400)
ax = plt.axes(projection='3d')
ax.plot_surface(x_dense, y_dense, z_dense ,cmap='viridis', edgecolor='none')
ax.invert_xaxis()
ax.set_title('Surface plot')
plt.show()
