import yt
import numpy as np

loc='/share/Part1/guido/harris_iso/test/md_hdf5_plt_cnt_0000'


ds       =yt.load(loc)
ray      =ds.ortho_ray(0,[0,0])

by  =ray[('flash','magy')]
P   =ray[('flash','pres')] #gas pressure
P_B =by**2/(8*np.pi) # magnetic pressure (cgs)
P_t =P+P_B # total pressure
print("P: {}".format(P))
print("P_B: {}".format(P_B))
print("P_t: {}".format(P_t))