from math import pi
import matplotlib
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
#from basic_units import radians, degrees, cos

x = [val*np.pi for val in np.arange(0, 4, 0.01)]
phase = np.pi/2*np.ones(len(x))
#print(x)

a = 1.

x1 = a * np.cos(x - phase)
x2 = a * np.cos(x)

fig, (ax1, ax2) = plt.subplots(2, sharex = True)

ax1.plot(x, x1, lw=2, c='k', xunits='radians')
ax1.set_ylabel(r'$\chi(x)$',fontsize=14)
ax1.set_xticks([0., .5*np.pi, pi, 1.5*np.pi, 2.*pi, 2.5*np.pi, 3.*np.pi, 3.5*np.pi, 4.*np.pi])
ax1.tick_params(labelsize=14)
ax2.plot(x, x2, lw=2, c='k', xunits='radians')
ax2.set_ylabel(r'$P(x)$',fontsize=14)
ax2.set_xticks([0., .5*np.pi, pi, 1.5*np.pi, 2.*pi, 2.5*np.pi, 3.*np.pi, 3.5*np.pi, 4.*np.pi])
ax2.set_xticklabels([ '0', r'$\frac{\pi}{2}$', r'$\pi$', r'$\frac{3}{2}\pi$', r'$2\pi$', r'$\frac{5}{2}\pi$', r'$3\pi$', r'$\frac{7}{2}\pi$', r'$4\pi$'], fontsize=14)
ax2.tick_params(labelsize=14)
ax2.set_xlabel('x', fontsize=14)
plt.subplots_adjust(hspace=0)
plt.tight_layout()
#plt.legend()
plt.savefig('ausbreitung_wellen_I.eps')
plt.show()