import numpy as np import matplotlib.pyplot as plt import scipy.special as sp  X = np.arange(0,21)  plt.rc('text', usetex = True) plt.rc('font', family = 'serif', size = 12)  ##                                                                                 ## CDF                                                                             ##   col = {1: 'orange', 4: 'purple', 10: 'lightblue'}  plt.clf() plt.figure(figsize=(4,3.2)) plt.axes([0.17,0.13,0.79,0.8])  A = [] for L in 1,4,10:      P = -L + X*np.log(L) - sp.gammaln(X+1)     P = np.exp(P)     P = np.cumsum(P)      for k in range(1,len(X)):         plt.plot([k-1,k], [P[k-1],P[k-1]], '-', color='grey', label = '_nolegend_')      a = plt.plot(X, P, 'o', color=col[L], markeredgecolor='k', markeredgewidth=0.5)     A.append(a)  plt.xlabel("$k$") plt.ylabel(u"$P(X\le k)$")  bx = plt.legend((r"$\lambda=1$", r"$\lambda=4$", r"$\lambda=10$"),\                 numpoints=1, handletextpad=0, loc="lower right") bx.draw_frame(False) plt.xlim([-1,21]) plt.ylim([0,1])  plt.savefig("poisson_cdf.pdf") plt.savefig("poisson_cdf.svg")