#! /usr/bin/env python # def polygon_contains_point ( x, y, px, py ): #*****************************************************************************80 # ## POLYGON_CONTAINS_POINT finds if a point is inside a polygon. # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 05 November 2016 # # Author: # # John Burkardt # # Parameters: # # Input, real X, Y, the coordinates of the point to be tested. # # Input, real PX(N), PY(N), the coordinates of the vertices of the polygon. # # Output, logical INSIDE, is TRUE if the point is inside the polygon. # n = len ( px ) inside = False px1 = px[0] py1 = py[0] xints = x - 1.0 for i in range ( 0, n + 1 ): px2 = px[i%n] py2 = py[i%n] if ( min ( py1, py2 ) < y ): if ( y <= max ( py1, py2 ) ): if ( x <= max ( px1, px2 ) ): if ( py1 != py2 ): xints = ( y - py1 ) * ( px2 - px1 ) / ( py2 - py1 ) + px1 if ( px1 == px2 or x <= xints ): inside = not inside px1 = px2 py1 = py2 return inside def polygon_contains_point_test ( ): #*****************************************************************************80 # ## POLYGON_CONTAINS_POINT_TEST tests POLYGON_CONTAINS_POINT. # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 05 November 2016 # # Author: # # John Burkardt # import numpy as np import platform from r8vec2_print import r8vec2_print n = 5 test_num = 4 x_test = np.array ( [ 1.0, 3.0, 0.0, 0.5 ] ) y_test = np.array ( [ 1.0, 4.0, 2.0, -0.25 ] ) px = np.array ( [ 0.0, 1.0, 2.0, 1.0, 0.0 ] ) py = np.array ( [ 0.0, 0.0, 1.0, 2.0, 2.0 ] ) print ( '' ) print ( 'POLYGON_CONTAINS_POINT_TEST' ) print ( ' Python version: %s' % ( platform.python_version ( ) ) ) print ( ' POLYGON_CONTAINS_POINT determines if' ) print ( ' a point is in a polygon.' ) r8vec2_print ( n, px, py, ' The polygon vertices:' ) print ( '' ) print ( ' X Y Inside?' ) print ( '' ) for test in range ( 0, test_num ): x = x_test[test] y = y_test[test] inside = polygon_contains_point ( x, y, px, py ) print ( ' %8.2f %8.2f %s' % ( x, y, inside ) ) # # Terminate. # print ( '' ) print ( 'POLYGON_CONTAINS_POINT_TEST' ) print ( ' Normal end of execution.' ) return if ( __name__ == '__main__' ): from timestamp import timestamp timestamp ( ) polygon_contains_point_test ( ) timestamp ( )