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from haystack.constants import WGS_84_SRID
from haystack.exceptions import SpatialError
def ensure_geometry(geom):
"""
Makes sure the parameter passed in looks like a GEOS ``GEOSGeometry``.
"""
if not hasattr(geom, "geom_type"):
raise SpatialError("Point '%s' doesn't appear to be a GEOS geometry." % geom)
return geom
def ensure_point(geom):
"""
Makes sure the parameter passed in looks like a GEOS ``Point``.
"""
ensure_geometry(geom)
if geom.geom_type != "Point":
raise SpatialError("Provided geometry '%s' is not a 'Point'." % geom)
return geom
def ensure_wgs84(point):
"""
Ensures the point passed in is a GEOS ``Point`` & returns that point's
data is in the WGS-84 spatial reference.
"""
ensure_point(point)
# Clone it so we don't alter the original, in case they're using it for
# something else.
new_point = point.clone()
if not new_point.srid:
# It has no spatial reference id. Assume WGS-84.
new_point.srid = WGS_84_SRID
elif new_point.srid != WGS_84_SRID:
# Transform it to get to the right system.
new_point.transform(WGS_84_SRID)
return new_point
def ensure_distance(dist):
"""
Makes sure the parameter passed in is a 'Distance' object.
"""
try:
# Since we mostly only care about the ``.km`` attribute, make sure
# it's there.
dist.km
except AttributeError:
raise SpatialError("'%s' does not appear to be a 'Distance' object." % dist)
return dist
def generate_bounding_box(bottom_left, top_right):
"""
Takes two opposite corners of a bounding box (order matters!) & generates
a two-tuple of the correct coordinates for the bounding box.
The two-tuple is in the form ``((min_lat, min_lng), (max_lat, max_lng))``.
"""
west, lat_1 = bottom_left.coords
east, lat_2 = top_right.coords
min_lat, max_lat = min(lat_1, lat_2), max(lat_1, lat_2)
return ((min_lat, west), (max_lat, east))
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