Optimize_curve

from scipy import optimize
import matplotlib.pyplot as plt
import numpy as np


y = np.array([20.0, 20.4, 20.9, 20.8, 20.3, 18.7, 18.8, 18.9, 18.0, 18.4, 18.5])
data = np.array(list(range(len(y))), dtype=np.float_)


def func(x, k):
    return k


p, e = optimize.curve_fit(func, data, y)
plt.plot(y, "o")
plt.plot(data, [p]*len(y))
plt.show()