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

#*****************************************************************************80
#
## least_squares_plots() compares data, a formula, and a least squares approximation.
#
#  Licensing:
#
#    This code is distributed under the MIT license.
#
#  Modified:
#
#    03 October 2026
#
#  Author:
#
#    John Burkardt
#
  import matplotlib
  import numpy as np
  import platform

  print ( '' )
  print ( 'least_squares_plots():' )
  print ( '  numpy version:      ' + np.version.version )
  print ( '  python version:     ' + platform.python_version ( ) )
  print ( '  On a single picture, plot:' )
  print ( '  * 15 data points (X,Y).\n' );
  print ( '  * the least squares line Y=A*X+B.\n' );
  print ( '  * the exact formula Y=1/2*X^2 + 1.\n' );
#
#  Set filenames.
#
  header = 'least_squares'
  command_filename = header + '_commands.txt'
  data1_filename = header + '1_data.txt'
  data2_filename = header + '2_data.txt'
  data3_filename = header + '3_data.txt'
  graphic_filename = header + '_plots.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 "Formula (green), Data (blue), least squares fit (red)"\n' )
  command_unit.write ( 'set grid\n' )
  command_unit.write ( 'set timestamp\n' )
  command_unit.write ( 'set key on\n' )
  command_unit.write ( 'set style data lines\n' )

  command_unit.write ( 'plot "' + data1_filename \
    + '" using 1:2 with points lw 3 lt rgb "blue" title "Data", \\\n' )
  command_unit.write ( '     "' + data2_filename \
    + '" using 1:2 with lines lw 3 lt rgb "red" title "Least Squares Line", \\\n' )
  command_unit.write ( '     "' + data3_filename \
    + '" using 1:2 with lines lw 3 lt rgb "green" title "Exact Formula"\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 ( )
  drug_dosage_plots ( )
  timestamp ( )