2d_area_from_list.py

# http://www.mathopenref.com/coordpolygonarea.html
from mathutils import Vector

def calc_area_from_2d_colist(v):
    sum = 0
    n = len(v)
    for i in range(n-1):
        sum += ((v[i][0] * v[i+1][1]) - (v[i][1] * v[i+1][0]))
    sum += ((v[n-1][0] * v[0][1]) - (v[n-1][1] * v[0][0]))
    return abs(sum / 2)

def calc_area_from_2d_vectorlist(v):
    sum = 0
    n = len(v)
    for i in range(n-1):
        sum += ((v[i].x * v[i+1].y) - (v[i].y * v[i+1].x))
    sum += ((v[n-1].x * v[0].y) - (v[n-1].y * v[0].x))
    return abs(sum / 2)


cl = [[3, 7], [9, 7], [11, 2], [2, 2]]
f = calc_area_from_2d_colist(cl)
print(f)

vl = [Vector((3, 7)), Vector((9, 7)), Vector((11, 2)), Vector((2, 2))]
f = calc_area_from_2d_vectorlist(vl)
print(f)