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

#*****************************************************************************80
#
## correlation_heat_map() creates a heat map of a correlation matrix.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    17 September 2026
#
#  Author:
#
#    John Burkardt
#
  import matplotlib
  import numpy as np
  import platform

  print ( '' )
  print ( 'correlation_heat_map():' )
  print ( '  matplotlib version: ' + matplotlib.__version__ )
  print ( '  numpy version:      ' + np.version.version )
  print ( '  python version:     ' + platform.python_version ( ) )
  print ( '  Heat map of a correlation matrix using gnuplot().' )
#
#  Set filenames.
#
  header = 'correlation'
  command_filename = header + '_commands.txt'
  data_filename = header + '_data.txt'
  graphic_filename = header + '_heat_map.png'
#
#  Create commands.
#
  command_unit = open ( command_filename, 'wt' )

  command_unit.write ( '# ' + command_filename + '\n' )
  command_unit.write ( '#\n' )
  command_unit.write ( '# Usage:\n' )
  command_unit.write ( '#  gnuplot < ' + command_filename + '\n' )
  command_unit.write ( '#\n' )
  command_unit.write ( 'set term png\n' )
  command_unit.write ( 'set output "' + graphic_filename + '"\n' )
  command_unit.write ( 'set xlabel "<--- X --->"\n' )
  command_unit.write ( 'set ylabel "<--- Y --->"\n' )
  command_unit.write ( 'set title "Heat map of correlation data"\n' )
  command_unit.write ( 'set timestamp\n' )
  command_unit.write ( 'unset key\n' )
  command_unit.write ( 'set tic scale 0\n' )
  command_unit.write ( 'set palette rgbformula 21, 22, 23\n' )
  cmin = 0.28
  cmax = 1.00
  command_unit.write ( 'set cbrange[%g:%g]\n' % ( cmin, cmax ) )
  command_unit.write ( 'unset cbtics\n' )
  xmin = -0.5
  xmax = 7.5
  ymin = -0.5
  ymax = 7.5
  command_unit.write ( 'set xrange [%g:%g]\n' % ( xmin, xmax ) )
  command_unit.write ( 'set yrange [%g:%g]\n' % ( ymin, ymax ) )
  command_unit.write ( 'set size square\n' )
  command_unit.write ( 'set view map\n' )
  command_unit.write ( 'splot "' + data_filename + '" matrix with image\n' )

  command_unit.write ( 'quit\n' )

  command_unit.close ( )
  print ( '  Created command file "' + command_filename + '"' )

  return

def timestamp ( ):

#*****************************************************************************80
#
## timestamp() prints the date as a timestamp.
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    21 August 2019
#
#  Author:
#
#    John Burkardt
#
  import time

  t = time.time ( )
  print ( time.ctime ( t ) )

  return

if ( __name__ == '__main__' ):
  timestamp ( )
  correlation_heat_map ( )
  timestamp ( )