Coverage for pyguymer3/geo/_area.py: 100%

1#!/usr/bin/env python3 

2 

3# Define function ... 

4def _area( 

5 triangle, 

6 /, 

7 *, 

8 eps = 1.0e-12, 

9 nIter = 100, 

10): 

11 """Find the area of a triangle. 

12 

13 Parameters 

14 ---------- 

15 triangle : shapely.geometry.polygon.Polygon 

16 the triangle 

17 eps : float, optional 

18 the tolerance of the Vincenty formula iterations 

19 nIter : int, optional 

20 the maximum number of iterations (particularly the Vincenty formula) 

21 

22 Returns 

23 ------- 

24 area : float 

25 the area (in metres-squared) 

26 

27 Notes 

28 ----- 

29 Copyright 2017 Thomas Guymer [1]_ 

30 

31 References 

32 ---------- 

33 .. [1] PyGuymer3, https://github.com/Guymer/PyGuymer3 

34 """ 

35 

36 # Import standard modules ... 

37 import math 

38 

39 # Import sub-functions ... 

40 from .calc_dist_between_two_locs import calc_dist_between_two_locs 

41 

42 # Check inputs ... 

43 assert len(triangle.exterior.coords) == 4, "\"triangle\" is not a triangle" 

44 

45 # ************************************************************************** 

46 

47 # Find the distance from the second point to the first point, and the 

48 # bearing of the first point as viewed from the second point ... 

49 a, bearing1, _ = calc_dist_between_two_locs( 

50 triangle.exterior.coords[1][0], 

51 triangle.exterior.coords[1][1], 

52 triangle.exterior.coords[0][0], 

53 triangle.exterior.coords[0][1], 

54 eps = eps, 

55 nIter = nIter, 

56 ) # [m], [°] 

57 

58 # Find the distance from the second point to the third point, and the 

59 # bearing of the third point as viewed from the second point ... 

60 b, bearing2, _ = calc_dist_between_two_locs( 

61 triangle.exterior.coords[1][0], 

62 triangle.exterior.coords[1][1], 

63 triangle.exterior.coords[2][0], 

64 triangle.exterior.coords[2][1], 

65 eps = eps, 

66 nIter = nIter, 

67 ) # [m], [°] 

68 

69 # Use the two bearings to find the interior angle between the first and 

70 # third points ... 

71 C = (bearing2 - bearing1) % 180.0 # [°] 

72 

73 # Return answer ... 

74 return 0.5 * a * b * math.sin(math.radians(C))