Python, Chaco, TRaits(UI) -based interactive Voigt profile editor. Good to play around with to understand how b and N affect the profile.

vp-interactive.py

#!/usr/bin/env python
# encoding: utf-8
# Copyright 2013, 2016 T. Emil Rivera-Thorsen
# trive@astro.su.se

''' To run: python vp-interactive-py
'''

import scipy as sp
import scipy.constants as con
from traits.api import *
from traitsui.api import View, RevertButton, OKButton, CancelButton, Item
from chaco.chaco_plot_editor import ChacoPlotItem

# cgs units (required in T-G voigt implementation):
cgsc = 2.998e10
cgsme = 9.1095e-28
cgse = 4.8032e-10


# Voigt-Hjerting function, as approximate by Tepper-Garcia 2006:
def H(a, x):
    """ The H(a, u) function of Tepper Garcia 2006
    """
    P = x ** 2
    H0 = sp.e ** (-(x ** 2))
    Q = 1.5 / x ** 2
    H = H0 - a / sp.sqrt(sp.pi) / P * \
        (H0 * H0 * (4 * P * P + 7 * P + 4 + Q) - Q - 1)
    return H

# Class that handles user interacting and calculations that are best done
# inside said class. Plus shows the outpot.
# Hooray for the Enthought Tool Suite!
class VoigtEdit(HasTraits):
    """The interface to edit the thingie.
    """
    pos = Range(800., 25000.)
    z = Range(0., 10.)
    N = Range(1.e6, 5e22)
    B = Range(1., 1000)  # In cgs. Must be conv to km/s before passed on.
    b = Property(Float, depends_on=['B'])  # Holds the cm/s version of B.
    f = Float
    g = Float
    # The rest are properties of the above Traits.
    vp = Property(Array, depends_on=['C', 'a', 'N', 'x'])
    # or Ca instead of c and a
    wl = Property(Array, depends_on=['pos'])
    x = Property(Array, depends_on=['pos', 'dwld'])
    C = Property(Float, depends_on=['f', 'g'])
    wavlen = Property(Array, depends_on=['wl', 'z'])
    dwld = Property(Float, depends_on=['b', 'wl0'])
    a = Property(Float, depends_on=['wl0', 'g', 'b'])
    wl0 = Property(Float, depends_on=['pos'])
    Ca = Property(Float, depends_on=['f', 'b', 'wl0'])
    fake_x = Property(Array, depends_on=['x'])

    def _get_b(self):
        return self.B * 10000.  # km/s -> cm/s

    def _pos_default(self):
        return 1215.67    # rest wl of line center in Å

    def _N_default(self):
        return 14.5e20

    def _b_default(self):
        return 20.

    def _z_default(self):
        return 0.

    def _f_default(self):
        f = 0.416    # Write different getter if other than Lyman Alpha is wanted.
        return f

    def _g_default(self):
        g = 6.265e8  # Write different getter if other than Lyman Alpha is wanted.
        return g

    def _get_wl0(self):
        return self.pos * 1.e-10

    def _get_wl(self):
        return sp.linspace(self.pos - 100, self.pos + 100, 50000) * 1.e-10

    def _get_dwld(self):
        return self.b * self.wl0 / con.c

    def _get_x(self):
        return (self.wl - self.wl0) / self.dwld

    def _get_C(self):
        return 4 * sp.pi * cgse * self.f / (cgsme * cgsc * self.g)

    def _get_Ca(self):
        Ca = cgse ** 2 / (cgsme * cgsc) * sp.sqrt(sp.pi ** 3) / sp.pi * self.f \
            * self.wl0 / self.b
        return Ca

    def _get_a(self):
        return self.wl0 * self.g / (4 * sp.pi * self.b)

    def _get_wavlen(self):
        return self.wl * 1.e10 * (1. + self.z)

    def _get_fake_x(self):
        return self.x * 1.e10

    def _get_vp(self):
        return sp.exp(-self.Ca * self.N * H(self.a, self.x))

    view = View(
        ChacoPlotItem(
            'wavlen', 'vp', y_bounds=(-.2, 1.2),
            y_auto=False,
            show_label=False, x_label='wavelength',
            width=750, height=500,
            y_label='relative flux'
        ),
        Item('z'),
        Item('N', label='N, cm^-2'),
        Item('B', label='b, km/s'),
        resizable=True,
        title='Voigt Profile editor',
        buttons=[RevertButton, CancelButton, OKButton]
    )

# Just a little demo.
if __name__ == '__main__':
    v = VoigtEdit()
    v.configure_traits()