draw_sky2.py

import matplotlib.pyplot as plt
from matplotlib.patches import Ellipse
import numpy as np

def draw_sky(galaxies):
    """adapted from Vishal Goklani"""
    size_multiplier = 45
    fig = plt.figure(figsize=(10,10))
    ax = fig.add_subplot(111, aspect='equal')
    n = galaxies.shape[0]
    for i in range(n):
        _g = galaxies[i,:]
        x,y = _g[0], _g[1]
        d = np.sqrt( _g[2]**2 + _g[3]**2 )
        a = 1.0/ ( 1 - d )
        b = 1.0/( 1 + d)
        theta = np.degrees( np.arctan2( _g[3], _g[2])*0.5 )
        
        ax.add_patch( Ellipse(xy=(x, y), width=size_multiplier*a, height=size_multiplier*b, angle=theta) )
    ax.autoscale_view(tight=True)
    
    return fig