Trying to make Kaeri-like plots

xsplt.py

from pyne.endf import Library
from pyne import nucname as nn
import matplotlib.pyplot as plt
import os
from urllib import urlretrieve

nucs = ['U235']
nmt = 18 # for (z, fission)

for nuc in nucs:
    f = '{}.txt'.format(nuc)
    if not os.path.isfile(f):
        root = "http://t2.lanl.gov/nis/data/data/ENDFB-VII.1-neutron"
        pth = "/".join([root, nn.zz_name[nn.znum(nuc)], str(nn.anum(nuc))]) 
        urlretrieve(pth, f)

fig = plt.figure()
for nuc in nucs:
    lib = Library('{}.txt'.format(nuc))    
    data = lib.get_xs(nn.id(nuc), nmt)[0]
    x, y = data['e_int'], data['xs']
    plt.step(x, y, where='pre', label=nuc, figure=fig)
plt.xscale('log')
plt.yscale('log')
plt.show()