Matplotlib で Contour を描く (例題; コンプトン散乱の反跳電子)

データ解析

contour を描いてみた覚え書き。式は以下ね。



\frac{E_e}{m_ec^2}=\frac{\gamma^2(1-\cos \theta)}{1 + \gamma(1-\cos \theta)}



contour は numpy の meshgrid として以下が参考になります。
http://docs.scipy.org/doc/numpy/reference/generated/numpy.meshgrid.html

import numpy 
import pylab 

def electron_energy(gamma, theta):
    numerator   = gamma**2*(1-numpy.cos(theta))
    denominator = 1 + gamma * (1-numpy.cos(theta))
    electron_energy = numerator / denominator
    # in a unit of m_ec^2 
    return electron_energy 

fig = pylab.plt.figure()

gamma_min = 0
gamma_max = 1.9
gamma_del = 0.1
theta_min = 0
theta_max = 180
theta_del = 1
x  = numpy.arange(gamma_min, gamma_max, gamma_del)
y  = numpy.arange(theta_min, theta_max, theta_del)
xx, yy = numpy.meshgrid(x,y)
zz = electron_energy(xx, numpy.radians(yy))
print zz

cont = pylab.plt.contour(xx, yy, zz)
pylab.clabel(cont, inline=2, fontsize=13)
pylab.grid(True)
pylab.title("Recoil Electron Energy $E_e$ ($m_ec^2$)",  fontsize=12, fontname='serif')
pylab.xlabel("Normalized Input Photon Energy ($m_ec^2$)", fontsize=12, fontname='serif')
pylab.ylabel("Scater Angle of the Photon ($\degree$)",  fontsize=12, fontname='serif')

fig.savefig("compton_electron_energy_contour.png", format='png')