#! /usr/bin/env python3
#
def faithful_data ( ):

#*****************************************************************************80
#
## faithful_data() displays the Old Faithful data.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    21 January 2022
#
#  Author:
#
#    John Burkardt
#
  import matplotlib.pyplot as plt
  import numpy as np
  import platform

  print ( '' )
  print ( 'faithful_plot:' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  Display Old Faithful (Erupt,Quiet) observations.' )
#
#  Read the data.
#
  data = np.loadtxt ( 'faithful_data.txt' )
#
#  Create x and y.
#
  x = data[:,0]
  y = data[:,1]

  plt.plot ( x, y, 'k.', markersize = 10 )
  plt.xlabel ( '<-- Erupt -->', fontsize = 16 )
  plt.ylabel ( '<-- Quiet -->', fontsize = 16 )
  plt.title ( 'Old Faithful eruptions (unscaled)', fontsize = 16 )
  plt.grid ( True )
  plt.axis ( 'equal' )
  filename = 'faithful_data_unscaled.png'
  plt.savefig ( filename )
  print ( '  Graphics saved as "%s"' % ( filename ) )
  plt.show ( )
  plt.clf ( )

  plt.plot ( x, y, 'k.', markersize = 10 )
  plt.xlabel ( '<-- Erupt -->', fontsize = 16 )
  plt.ylabel ( '<-- Quiet -->', fontsize = 16 )
  plt.title ( 'Old Faithful eruptions (scaled)', fontsize = 16 )
  plt.grid ( True )
  filename = 'faithful_data_scaled.png'
  plt.savefig ( filename )
  print ( '  Graphics saved as "%s"' % ( filename ) )
  plt.show ( )
  plt.clf ( )

  x = ( x - np.min ( x ) ) / ( np.max ( x ) - np.min ( x ) )
  y = ( y - np.min ( y ) ) / ( np.max ( y ) - np.min ( y ) )
  plt.plot ( x, y, 'k.', markersize = 10 )
  plt.xlabel ( '<-- Erupt -->', fontsize = 16 )
  plt.ylabel ( '<-- Quiet -->', fontsize = 16 )
  plt.title ( 'Old Faithful eruptions (normalized)', fontsize = 16 )
  plt.grid ( True )
  filename = 'faithful_data_normalized.png'
  plt.savefig ( filename )
  print ( '  Graphics saved as "%s"' % ( filename ) )
  plt.show ( )
  plt.clf ( )
#
#  Terminate.
#
  print ( '' )
  print ( 'faithful_data():' )
  print ( '  Normal end of execution.' )

  return

if ( __name__ == '__main__' ):
  faithful_data ( )