old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  """A Mandelbrot set demo"""
  
  # Copyright (c) 2012 Jérémie DECOCK (http://www.jdhp.org)
  
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
   
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  
  import numpy as np
  import matplotlib.pyplot as plt
  from mpl_toolkits.mplot3d import axes3d
  from matplotlib import cm
  
  REAL_RANGE = np.arange(-2.0, 1.0, 0.05).tolist()
  IMAG_RANGE = np.arange(-1.2, 1.2, 0.05).tolist()
  
  EPSILON_MAX = 2.
  NUM_IT_MAX = 32
  
  Z_INIT = complex(0, 0)
  
  def mandelbrot(x, y):
      it = 0
      z = Z_INIT
      c = complex(x, y)
  
      # Rem: abs(z) = |z| = math.sqrt(pow(z.imag,2) + pow(z.real,2))
      while it < NUM_IT_MAX and abs(z) <= EPSILON_MAX:
          z = pow(z, 2) + c
          it += 1
  
      # To print all levels
      return it
  
      ## To print only the level N
      #if it < N:
      #    return 1
      #else:
      #    return 0
  
  def main():
      """Main function"""
  
      # Compute datas #############
  
      colorgrid = np.zeros([len(REAL_RANGE), len(IMAG_RANGE)]).T
      xgrid, ygrid = np.meshgrid(REAL_RANGE, IMAG_RANGE)
  
      for x_index, x in enumerate(REAL_RANGE):
          for y_index, y in enumerate(IMAG_RANGE):
              colorgrid[y_index, x_index] = mandelbrot(x, y)
  
  
      # Plot data #################
  
      fig = plt.figure()
      ax = axes3d.Axes3D(fig)
  
      # Plot mean surface
  
      ax.plot_surface(xgrid, ygrid, colorgrid, cmap=cm.jet, rstride=1, cstride=1, color='b', shade=True)
  
      # Title, etc.
  
      plt.title("Mandelbrot set")
      ax.set_xlabel("Re(c)")
      ax.set_ylabel("Im(c)")
      ax.set_zlabel("Color")
  
      plt.savefig("mandelbrot.png")
  
      plt.show()
  
  if __name__ == '__main__':
      main()
  
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  """A Mandelbrot set demo"""
  
  # Copyright (c) 2012 Jérémie DECOCK (http://www.jdhp.org)
  
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
   
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  
  import numpy as np
  import matplotlib.pyplot as plt
  from mpl_toolkits.mplot3d import axes3d
  from matplotlib import cm
  
  REAL_RANGE = np.arange(-2.0, 1.0, 0.05).tolist()
  IMAG_RANGE = np.arange(-1.2, 1.2, 0.05).tolist()
  
  EPSILON_MAX = 2.
  NUM_IT_MAX = 32
  
  Z_INIT = complex(0, 0)
  
  def mandelbrot(x, y):
      it = 0
      z = Z_INIT
      c = complex(x, y)
  
      # Rem: abs(z) = |z| = math.sqrt(pow(z.imag,2) + pow(z.real,2))
      while it < NUM_IT_MAX and abs(z) <= EPSILON_MAX:
          z = pow(z, 2) + c
          it += 1
  
      # To print all levels
      return it
  
      ## To print only the level N
      #if it < N:
      #    return 1
      #else:
      #    return 0
  
  def main():
      """Main function"""
  
      # Compute datas #############
  
      xgrid, ygrid = np.meshgrid(REAL_RANGE, IMAG_RANGE)
  
      data = np.array([mandelbrot(x, y) for y in IMAG_RANGE for x in REAL_RANGE]).reshape(len(IMAG_RANGE), len(REAL_RANGE))
  
      # Plot data #################
  
      fig = plt.figure()
      ax = axes3d.Axes3D(fig)
  
      # Plot mean surface
  
      ax.plot_surface(xgrid, ygrid, data, cmap=cm.jet, rstride=1, cstride=1, color='b', shade=True)
  
      # Title, etc.
  
      plt.title("Mandelbrot set")
      ax.set_xlabel("Re(c)")
      ax.set_ylabel("Im(c)")
      ax.set_zlabel("Color")
  
      plt.savefig("mandelbrot.png")
  
      plt.show()
  
  if __name__ == '__main__':
      main()
  
  
subject: Use a more 'pythonic' list construction.