old_contents: """
  SDSS Galaxy Colors
  ------------------
  The function :func:`fetch_sdss_galaxy_colors` used below actually queries
  the SDSS CASjobs server for the colors of the 50,000 galaxies.  Below we
  extract the :math:`u - g` and :math:`g - r` colors for 5000 stars, and
  scatter-plot the results
  """
  # Author: Jake VanderPlas <vanderplas@astro.washington.edu>
  # License: BSD
  #   The figure is an example from astroML: see http://astroML.github.com
  import numpy as np
  from matplotlib import pyplot as plt
  
  from sklearn.neighbors import KNeighborsRegressor
  
  from astroML.datasets import fetch_sdss_galaxy_colors
  
  #------------------------------------------------------------
  # Download data
  data = fetch_sdss_galaxy_colors()
  data = data[::10]  # truncate for plotting
  
  # Extract colors and spectral class
  ug = data['u'] - data['g']
  gr = data['g'] - data['r']
  spec_class = data['specClass']
  
  stars = (spec_class == 2)
  qsos = (spec_class == 3)
  
  #------------------------------------------------------------
  # Prepare plot
  fig = plt.figure()
  ax = fig.add_subplot(111)
  
  ax.set_xlim(-0.5, 2.5)
  ax.set_ylim(-0.5, 1.5)
  
  ax.plot(ug[stars], gr[stars], '.', ms=4, c='b', label='stars')
  ax.plot(ug[qsos], gr[qsos], '.', ms=4, c='r', label='qsos')
  
  ax.legend(loc=2)
  
  ax.set_xlabel('$u-g$')
  ax.set_ylabel('$g-r$')
  
  plt.show()
  
new_contents: """
  SDSS Galaxy Colors
  ------------------
  The function :func:`fetch_sdss_galaxy_colors` used below actually queries
  the SDSS CASjobs server for the colors of the 50,000 galaxies.  Below we
  extract the :math:`u - g` and :math:`g - r` colors for 5000 objects, and
  scatter-plot the results.
  """
  # Author: Jake VanderPlas <vanderplas@astro.washington.edu>
  # License: BSD
  #   The figure is an example from astroML: see http://astroML.github.com
  from matplotlib import pyplot as plt
  
  from astroML.datasets import fetch_sdss_galaxy_colors
  
  #------------------------------------------------------------
  # Download data
  data = fetch_sdss_galaxy_colors()
  data = data[::10]  # truncate for plotting
  
  # Extract colors and spectral class
  ug = data['u'] - data['g']
  gr = data['g'] - data['r']
  spec_class = data['specClass']
  
  galaxies = (spec_class == 'GALAXY')
  qsos = (spec_class == 'QSO')
  
  #------------------------------------------------------------
  # Prepare plot
  fig = plt.figure()
  ax = fig.add_subplot(111)
  
  ax.set_xlim(-0.5, 2.5)
  ax.set_ylim(-0.5, 1.5)
  
  ax.plot(ug[galaxies], gr[galaxies], '.', ms=4, c='b', label='galaxies')
  ax.plot(ug[qsos], gr[qsos], '.', ms=4, c='r', label='qsos')
  
  ax.legend(loc=2)
  
  ax.set_xlabel('$u-g$')
  ax.set_ylabel('$g-r$')
  
  plt.show()
  
subject: Fix example to plot galaxies rather than stars (that were not queried)