#!/usr/bin/python
# -*- coding: utf8 -*-

import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
from math import *

code_website = 'http://commons.wikimedia.org/wiki/User:Geek3/mplwp'
try:
    import mplwp
except ImportError, er:
    print 'ImportError:', er
    print 'You need to download mplwp.py from', code_website
    exit(1)

name = 'mplwp_arcsec_piaxis.svg'
fig = mplwp.fig_standard(mpl)

# add pi to xaxis labels
def flabel(x, i):
    return u'{}\u03C0'.format(x).replace('-', u'\u2212')
fig.gca().yaxis.set_major_formatter(mpl.ticker.FuncFormatter(flabel))

# make space for labels
mplwp.move_axes(fig, 11, 0)
fig.gca().yaxis.set_major_locator(mpl.ticker.MultipleLocator(0.25))

xlim = -5,5; fig.gca().set_xlim(xlim)
ylim = -0.125,1.125; fig.gca().set_ylim(ylim)
mplwp.mark_axeszero(fig.gca())

def sec(y):
    a = cos(pi*y)
    if fabs(a) < 0.1: return float('NaN')
    return 1.0 / a
    
y = np.linspace(0, 1, 5001)
x = [sec(yy) for yy in y]

plt.plot(x, y, label='arcsec')
plt.plot([-1,1], [1,0], '.', color=fig.gca().lines[-1].get_color())
plt.legend(loc='upper right').get_frame().set_alpha(0.9)
    
plt.savefig(name)
mplwp.postprocess(name)