Python 线性插值，已知x求Y

import numpy as np
import matplotlib.pyplot as plt

y = np.array([0, 38.39, 71.41, 99.66, 123.67, 143.88, 160.61, 174.03, 184.16, 190.8, 193.52])
x = np.array([0, 0.37, 0.74, 1.11, 1.48, 1.85, 2.22, 2.59, 2.96, 3.33, 3.7])
plt.plot(x, y, '-')

y_val = 30
root = np.interp(y_val, y, x)
print(root)
plt.plot(root, y_val, marker="X")
plt.plot([root, root, 0], [0, y_val, y_val], "--")
plt.xlim(0, None)
plt.ylim(0, None)
plt.show()