3次元の散布図を補間

2次元の散布図を補間する例はたくさんあるけれど、3次元にはあまりないので。

3つの軸のどれかをX軸に選ぶのがおそらく一番簡単。

import numpy as np
import scipy.interpolate as itpl
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt

def show_points(points):
    fig = plt.figure()
    ax = fig.add_subplot(111, projection='3d')

    for i in points:
        x, y, z = i
        ax.scatter(x, y, z, marker='o')

    ax.set_xlabel('X')
    ax.set_xlim(0, 1)
    ax.set_ylabel('Y')
    ax.set_ylim(0, 1)
    ax.set_zlabel('Z')
    ax.set_zlim(0, 1)

    plt.show()


def gen_curve(n_point):
    x = np.linspace(0, 1, n_point)
    points = np.array([x, np.sin(x * np.pi / 2), np.cos(x * np.pi / 2)]).transpose((1, 0))
    return points

def main():
    points = gen_curve(10)
    show_points(points)
    f = itpl.interp1d(points[:,0], points[:,1:3], axis=0, kind='cubic')
    x = np.linspace(0, 1, 20)
    y = f(x)
    points2 = np.hstack((x.reshape(-1, 1), y))
    show_points(points2)

if __name__=='__main__':
    main()