def test_get_width_at_latitude(self):
"""
Tests method for finding the width of the bounding box at the given
latitude, in meters.
"""
bounds = Bounds(n_lat=50.0, s_lat=0.0, e_lng=50.0, w_lng=0.0)
width = bounds.get_width_at_latitude_m(25.0)
self.assertAlmostEqual(width, 5017040, delta=5)
def test_at_equator(self):
"""
Tests the function convert_circle_to_rectangle at the Equator.
This makes it easier to calculate expected values.
"""
coord = (-78.0, 0)
radius_m = 10000
square = shapes.convert_circle_to_rectangle(coord, radius_m)
# check that the shape is correct
self.assertEqual(shapes.is_rectangle(square[0]), True,
'Shape is not a rectangle')
# check that the rectangle center is at the original point
bounds = Bounds(*square.extent)
self.assertAlmostEqual(square.centroid[0], coord[0], places=6,
msg='The center longitude is incorrect')
self.assertAlmostEqual(square.centroid[1], coord[1], places=6,
msg='The center latitude is incorrect')
# check that rectangle has the correct area
area_in_sq_m = bounds.center_width_m * bounds.height_m
actual_sq_km = units.sq_meters_to_sq_km(area_in_sq_m)
expected_sq_km = (2 * radius_m / 1000)**2
self.assertAlmostEqual(actual_sq_km, expected_sq_km, delta=0.001)
# check that the rectangle contains the circle
radius_in_degrees = units.convert_meters_to_degrees(radius_m, 'down')
point = Point(coord)
circle = point.buffer(radius_in_degrees)
self.assertTrue(square.contains(circle))
def test_buffer(self):
"""
Tests method for buffering the bounds.
"""
bounds = Bounds(n_lat=28.0, s_lat=26.0, e_lng=0.0, w_lng=-2.0)
old_height = bounds.height_m
old_width = bounds.center_width_m
buffer_m = 10
bounds.buffer(buffer_m)
actual_height = bounds.height_m
actual_width = bounds.center_width_m
expected_height = old_height + (buffer_m * 2)
expected_width = old_width + (buffer_m * 2)
self.assertAlmostEqual(actual_height, expected_height, delta=0.001)
self.assertAlmostEqual(actual_width, expected_width, delta=0.001)
def test_center_width(self):
"""
Tests method for finding the average width of the bounding box in meters.
"""
bounds = Bounds(n_lat=50.0, s_lat=0.0, e_lng=25.0, w_lng=0.0)
expected = vincenty((25.0, 0), (25.0, 25.0)).meters
self.assertEqual(bounds.center_width_m, expected)
def convert_circle_to_rectangle(point, radius_m):
"""
(tuple(int or float, int or float), int or float) -> GEOSGeometry Polygon
Takes a circle as a (lng, lat) tuple and a radius in meters. Returns the
smallest rectangular Polygon that encompasses the circle.
"""
# reverse the lng, lat order to convert to geopy Point format
center = reverse_coordinate_order(point)
# create a geopy coordinate calculator for the given distance
calculator = vincenty(meters=radius_m)
# calculate points at the given distance in the cardinal directions
n_pt = calculator.destination(point=center, bearing=0)
s_pt = calculator.destination(point=center, bearing=180)
e_pt = calculator.destination(point=center, bearing=90)
w_pt = calculator.destination(point=center, bearing=270)
bounds = Bounds(n_lat=n_pt.latitude,
s_lat=s_pt.latitude,
e_lng=e_pt.longitude,
w_lng=w_pt.longitude)
return bounds.bounding_box
def create_buffered_bounds(polygon, buffer_m):
"""
Takes a GEOSGeometry Polygon and a buffer distance in meters.
Returns a Bounds object representing the polygon bounds buffered
by the specified distance.
"""
assert (isinstance(polygon, Polygon))
return Bounds(*polygon.extent).buffer(buffer_m)
def create_buffered_bounds(polygon, buffer_m):
"""
Takes a GEOSGeometry Polygon and a buffer distance in meters.
Returns a Bounds object representing the polygon bounds buffered
by the specified distance.
"""
if not isinstance(polygon, Polygon): # pragma: no cover
raise TypeError('object is not a Polygon')
return Bounds(*polygon.extent).buffer(buffer_m)
def test_default_corners(self):
"""
Tests the methods for getting corners using the default values for a
new Bounds instance.
"""
bounds = Bounds()
points = (bounds.sw_corner, bounds.nw_corner, bounds.ne_corner,
bounds.se_corner)
self.assertEqual(points, ((180.0, 90.0), (180.0, -90.0),
(-180.0, -90.0), (-180.0, 90.0)))
def test_height(self):
"""
Tests method for finding the height of the bounding box in meters.
"""
bounds = Bounds(n_lat=50.0, s_lat=0.0, e_lng=25.0, w_lng=0.0)
self.assertAlmostEqual(bounds.height_m, 5540850, delta=5)