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

  from scipy.spatial import ConvexHull
  import matplotlib.pyplot as plt
  import numpy as np

  points = np.loadtxt ( 'i18.txt' )
#
#  Display just the points.
#
  plt.clf ( )
  plt.plot ( points[:,0], points[:,1], 'o' )
  plt.grid ( 'True' )
  filename = 'i18_points.png'
  plt.savefig ( filename )
  print ( '  Graphics saved as "' + filename + '"' )
  plt.show ( )
  plt.close ( )
#
#  Compute the hull.
#
  hull = ConvexHull ( points )
#
#  Display points and hull.
#
  plt.clf ( )
  plt.plot ( points[:,0], points[:,1], 'o' )

  for simplex in hull.simplices:
    plt.plot ( points[simplex, 0], points[simplex, 1], 'k-' )

  plt.grid ( 'True' )
  filename = 'i18_convex_hull.png'
  plt.savefig ( filename )
  print ( '  Graphics saved as "' + filename + '"' )
  plt.show ( )
  plt.close ( )

  hull_size = hull.simplices.shape[0]
  print ( '  Number of points in convex hull boundary = ', hull_size )

  return

if ( __name__ == "__main__" ):
  convex_hull_test ( )