import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
lev = (np.arange(50)+1)*0.02

f=open('shallow2d.dat','rb')

buffer = np.fromfile(f,'i8',1)
m=buffer[0]
buffer = np.fromfile(f,'d',1)
dx=buffer[0]
L=dx*m
x=(np.arange(m)+0.5)*dx
x2=np.arange(m+1)*dx
xg = (np.arange(m)+0.5)*dx
yg = (np.arange(m)+0.5)*dx
XG, YG = np.meshgrid(xg, yg)
XG2, YG2 = np.meshgrid(x2, x2)
    
buffer = np.fromfile(f,'d',(m+1)*(m+1)*3)
var=buffer
var = var.reshape((m+1,m+1,3),order='F')
plt.cla()
plt.axis('scaled')    
plt.xlim(0, L)
plt.ylim(0, L)    
plt.contour(XG, YG, var[:m,:m,0].T, linewidths=1,levels=lev)
plt.quiver(XG2[::5,::5], YG2[::5,::5], var[::5,::5,1].T,var[::5,::5,2].T, scale=1,pivot='mid')        
plt.ylabel(r'$y$')
plt.xlabel(r'$x$')
t=0
plt.title(r'$t=$'+'{:.5f}'.format(t),loc='right',fontsize=10)    
#plt.pause(0.01)
plt.pause(100)
f.close()