https://stats.stackexchange.com/a/47782/69508

47782_69508.py

from scipy.stats import beta
import matplotlib.pyplot as plt
import numpy as np

params = [[81, 219],
          [82, 219],
          [81+100, 219+200]]

for a, b in params:

    fig, ax = plt.subplots(1, 1)

    x = np.linspace(0.15, 0.40, 10000)
    y = beta.pdf(x, a, b)

    ax.plot(x, y, 'k')
    ax.set_xlabel('x')
    if a != 181:
        ax.set_ylabel(f'dbeta(x, {a}, {b})')
    else:
        ax.set_ylabel(f'dbeta(x, 81 + 100, 219 + 200)')
    plt.show()