Graphing the "Coronavirus curve" with Python

sir_model.py

import matplotlib.pyplot as plt
import numpy as np
from scipy.integrate import odeint

MAX_TIME = 20.0

infected_start = 0.01

infection_rate = 2.5
recovery_rate = 0.3

susceptible_start = 1.0 - infected_start
recovered_start = 0.0

initial_state = [susceptible_start, infected_start, recovered_start]

state_change_rate = lambda state, _time: [
    -state[0] * state[1] * infection_rate,
    state[0] * state[1] * infection_rate - state[1] * recovery_rate,
    state[1] * recovery_rate,
]

time_series = np.linspace(0, MAX_TIME, 100)

state_series = odeint(state_change_rate, initial_state, time_series)

susceptible_series = state_series[:, 0]
infected_series = state_series[:, 1]
recovered_series = state_series[:, 2]

plt.plot(time_series, susceptible_series, label="Susceptible")
plt.plot(time_series, infected_series, label="Infected")
plt.plot(time_series, recovered_series, label="Recovered")

plt.xlabel("Time")
plt.ylabel("Population")
plt.legend()

plt.show()