import numpy as np
import math
import matplotlib.pyplot as plt
from scipy.stats import norm
from scipy.stats import poisson
import math
mu = 200
nMin = max(0, int(mu-4*math.sqrt(mu)))
nMax = int(mu+4*math.sqrt(mu))
n = np.linspace(nMin, nMax, nMax-nMin+1)
x = np.linspace(nMin, nMax, 1000)
ax = plt.subplot(111)
ax.plot(n, poisson.pmf(n,mu), label="Poisson", marker='o')
ax.plot(x, norm.pdf(x, scale=math.sqrt(mu), loc=mu), label="Gaussian")
ax.grid()
ax.legend()
_ = ax.set_ylim(bottom=0)