interval = 300
divided_list = [flux_maxij[i:i+interval] for i in range(0, len(flux_maxij), interval)]

您可以看到range如何接受三个参数: range(init_value, end_value, step_size)

x = np.array(range(0, len(flux_maxij), interval))
y = np.array([np.median(j) for j in divided_list])
plt.plot(x, y, 's')

然后一行变成:

plt.plot(np.array(range(0, len(flux_maxij), interval)), 
         np.array([np.median(j) for j in [flux_maxij[i:i+interval] for i in range(0, len(flux_maxij), interval)]]),
         's')