old_contents: import numpy as np
  import matplotlib.pyplot as plt
  import astropy.io.ascii as ascii
  
  
  data = ascii.read('test.dat')
  pyout = ascii.read('test.pyout')
  idlout = ascii.read('test.idlout')
  
  fig = plt.figure()
  ax = fig.add_subplot(111)
  ax.scatter(data['x'], data['y'], c='k')
  ax.errorbar(data['x'], data['y'], xerr=data['xsig'], yerr=data['ysig'], ls=' ', c='k')
  
  # Fix the plot boundaries and then plot the true line
  xlim = ax.get_xlim()
  ax.set_xlim(xlim)
  ylim = ax.get_ylim()
  ax.set_ylim(ylim)
  truex = np.array(xlim)
  truey = 4.0 + 3.0*truex
  ax.plot(truex, truey, c='k', lw=2)
  
  # Plot samples of the regression line
  samplex = truex
  for i in xrange(0, len(pyout), len(pyout)/50):
      sampley = pyout[i]['alpha'] + pyout[i]['beta'] * samplex
      ax.plot(samplex, sampley, c='b', alpha=0.1)
  
  for i in xrange(0, len(pyout), len(pyout)/50):
      sampley = idlout[i]['alpha'] + idlout[i]['beta'] * samplex
      ax.plot(samplex, sampley, c='r', alpha=0.1)
  
  
  plt.show()
  
new_contents: import numpy as np
  import matplotlib.pyplot as plt
  import astropy.io.ascii as ascii
  
  
  data = ascii.read('test.dat')
  pyout = ascii.read('test.pyout')
  idlout = ascii.read('test.idlout')
  
  fig = plt.figure()
  ax = fig.add_subplot(111)
  ax.scatter(data['x'], data['y'], c='k')
  ax.errorbar(data['x'], data['y'], xerr=data['xsig'], yerr=data['ysig'], ls=' ', c='k')
  
  # Fix the plot boundaries and then plot the true line
  xlim = ax.get_xlim()
  ax.set_xlim(xlim)
  ylim = ax.get_ylim()
  ax.set_ylim(ylim)
  truex = np.array(xlim)
  truey = 4.0 + 3.0*truex
  ax.plot(truex, truey, c='k', lw=2)
  
  # Plot samples of the regression line
  samplex = truex
  for i in range(0, len(pyout), len(pyout)//50):
      sampley = pyout[i]['alpha'] + pyout[i]['beta'] * samplex
      ax.plot(samplex, sampley, c='b', alpha=0.1)
  
  for i in range(0, len(pyout), len(pyout)//50):
      sampley = idlout[i]['alpha'] + idlout[i]['beta'] * samplex
      ax.plot(samplex, sampley, c='r', alpha=0.1)
  
  
  plt.show()
  
subject: update tests for py3