import matplotlib.pyplot as plt
import numpy as np
import scipy.stats as st
import arviz as az
plt.style.use('arviz-darkgrid')
x = np.linspace(0, 5, 200)
sigmas = [1., 1., 2., 1.]
nus = [.5, 1., 1., 30.]
for sigma, nu in zip(sigmas, nus):
    pdf = st.t.pdf(x, df=nu, loc=0, scale=sigma)
    plt.plot(x, pdf, label=r'$\sigma$ = {}, $\nu$ = {}'.format(sigma, nu))
plt.xlabel('x', fontsize=12)
plt.ylabel('f(x)', fontsize=12)
plt.legend(loc=1)
plt.show()