Python を使用して y = 0 の曲線の交点を正確に見つける方法

<code class="python">import numpy as np
import matplotlib.pyplot as plt
vertical_data = ...
gradient = ...
plt.plot(gradient, vertical_data)
plt.show()</code>

<code class="python">import numpy as np

def find_roots(x, y):
    # Compute the sign differences
    s = np.abs(np.diff(np.sign(y))).astype(bool)
    # Perform linear interpolation at sign changes
    return x[:-1][s] + np.diff(x)[s]/(np.abs(y[1:][s]/y[:-1][s])+1)</code>

<code class="python">z = find_roots(gradient, vertical_data)

plt.plot(gradient, vertical_data)
plt.plot(z, np.zeros(len(z)), marker="o", ls="", ms=4)
plt.show()</code>

<code class="python">plt.plot(vertical_data, gradient)
plt.plot(np.zeros(len(z)), z, marker="o", ls="", ms=4)
plt.show()</code>

<code class="python">y0 = 1.4
z = find_roots(gradient, vertical_data - y0)
plt.plot(z, np.zeros(len(z))+y0)</code>

<code class="python">y2 = ...
z = find_roots(gradient, y2 - y1)
plt.plot(gradient, y1)
plt.plot(gradient, y2, color="C2")
plt.plot(z, np.interp(z, gradient, y1), marker="o", ls="", ms=4, color="C1")</code>