Integrate the new Location class
- the old `UTMCoordinate` class becomes the new `Location` class - its main purpose is to represent locations in both lat-long coordinates as well as in the UTM system - remove `Address.__init__()` and `City.__init__()` methods as they are not executed for entries retrieved from the database - simplfiy the `Location.__init__()` => remove `relative_to` argument
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8 changed files with 198 additions and 157 deletions
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@ -1,6 +1,5 @@
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"""Provide the ORM's `Address` model."""
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from typing import Any
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import sqlalchemy as sa
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from sqlalchemy import orm
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@ -69,14 +68,9 @@ class Address(meta.Base):
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)
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pixels = orm.relationship('AddressPixelAssociation', back_populates='address')
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def __init__(self, *args: Any, **kwargs: Any) -> None:
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"""Create a new address."""
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# Call SQLAlchemy's default `.__init__()` method.
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super().__init__(*args, **kwargs)
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self._utm_coordinates = utils.UTMCoordinate(
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self.latitude, self.longitude, relative_to=self.city.as_origin,
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)
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# We do not implement a `.__init__()` method and leave that to SQLAlchemy.
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# Instead, we use `hasattr()` to check for uninitialized attributes.
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# grep:b1f68d24 pylint:disable=attribute-defined-outside-init
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def __repr__(self) -> str:
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"""Non-literal text representation."""
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@ -95,12 +89,39 @@ class Address(meta.Base):
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"""
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return self.id == self._primary_id
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@property
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def location(self) -> utils.Location:
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"""The location of the address.
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The returned `Location` object relates to `.city.viewport.southwest`.
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See also the `.x` and `.y` properties that are shortcuts for
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`.location.x` and `.location.y`.
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Implementation detail: This property is cached as none of the
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underlying attributes to calculate the value are to be changed.
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"""
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if not hasattr(self, '_location'): # noqa:WPS421 note:b1f68d24
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self._location = utils.Location(self.latitude, self.longitude)
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self._location.relate_to(self.city.as_xy_origin)
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return self._location
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@property
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def x(self) -> int: # noqa=WPS111
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"""The `.easting` of the address in meters, relative to the `.city`."""
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return self._utm_coordinates.x
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"""The relative x-coordinate within the `.city` in meters.
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On the implied x-y plane, the `.city`'s southwest corner is the origin.
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Shortcut for `.location.x`.
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"""
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return self.location.x
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@property
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def y(self) -> int: # noqa=WPS111
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"""The `.northing` of the address in meters, relative to the `.city`."""
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return self._utm_coordinates.y
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"""The relative y-coordinate within the `.city` in meters.
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On the implied x-y plane, the `.city`'s southwest corner is the origin.
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Shortcut for `.location.y`.
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"""
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return self.location.y
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@ -1,6 +1,6 @@
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"""Provide the ORM's `City` model."""
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from typing import Any, Dict
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from typing import Dict
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import sqlalchemy as sa
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from sqlalchemy import orm
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@ -47,60 +47,52 @@ class City(meta.Base):
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addresses = orm.relationship('Address', back_populates='city')
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grids = orm.relationship('Grid', back_populates='city')
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def __init__(self, *args: Any, **kwargs: Any) -> None:
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"""Create a new city."""
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# Call SQLAlchemy's default `.__init__()` method.
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super().__init__(*args, **kwargs)
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# Take the "lower left" of the viewport as the origin
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# of a Cartesian coordinate system.
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lower_left = self.viewport['southwest']
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self._origin = utils.UTMCoordinate(
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lower_left['latitude'], lower_left['longitude'],
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)
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# We do not implement a `.__init__()` method and leave that to SQLAlchemy.
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# Instead, we use `hasattr()` to check for uninitialized attributes.
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# grep:d334120e pylint:disable=attribute-defined-outside-init
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def __repr__(self) -> str:
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"""Non-literal text representation."""
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return '<{cls}({name})>'.format(cls=self.__class__.__name__, name=self.name)
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@property
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def location(self) -> Dict[str, float]:
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"""GPS location of the city's center.
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def center(self) -> utils.Location:
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"""Location of the city's center.
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Example:
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{"latitude": 48.856614, "longitude": 2.3522219}
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Implementation detail: This property is cached as none of the
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underlying attributes to calculate the value are to be changed.
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"""
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return {
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'latitude': self._center_latitude,
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'longitude': self._center_longitude,
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}
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if not hasattr(self, '_center'): # noqa:WPS421 note:d334120e
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self._center = utils.Location(
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self._center_latitude, self._center_longitude,
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)
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return self._center
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@property
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def viewport(self) -> Dict[str, Dict[str, float]]:
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def viewport(self) -> Dict[str, utils.Location]:
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"""Google Maps viewport of the city.
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Example:
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{
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'northeast': {'latitude': 48.9021449, 'longitude': 2.4699208},
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'southwest': {'latitude': 48.815573, 'longitude': 2.225193},
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Implementation detail: This property is cached as none of the
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underlying attributes to calculate the value are to be changed.
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"""
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if not hasattr(self, '_viewport'): # noqa:WPS421 note:d334120e
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self._viewport = {
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'northeast': utils.Location(
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self._northeast_latitude, self._northeast_longitude,
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),
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'southwest': utils.Location(
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self._southwest_latitude, self._southwest_longitude,
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),
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}
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""" # noqa:RST203
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return {
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'northeast': {
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'latitude': self._northeast_latitude,
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'longitude': self._northeast_longitude,
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},
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'southwest': {
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'latitude': self._southwest_latitude,
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'longitude': self._southwest_longitude,
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},
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}
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return self._viewport
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@property
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def as_origin(self) -> utils.UTMCoordinate:
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"""The lower left corner of the `.viewport` in UTM coordinates.
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def as_xy_origin(self) -> utils.Location:
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"""The southwest corner of the `.viewport`.
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This property serves as the `relative_to` argument to the
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`UTMConstructor` when representing an `Address` in the x-y plane.
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This property serves, for example, as the `other` argument to the
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`Location.relate_to()` method when representing an `Address`
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in the x-y plane.
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"""
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return self._origin
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return self.viewport['southwest']
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@ -1,3 +1,3 @@
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"""Utilities used by the ORM models."""
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from urban_meal_delivery.db.utils.coordinates import UTMCoordinate # noqa:F401
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from urban_meal_delivery.db.utils.locations import Location
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@ -1,4 +1,4 @@
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"""A `UTMCoordinate` class to unify working with coordinates."""
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"""A `Location` class to unify working with coordinates."""
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from __future__ import annotations
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@ -7,19 +7,27 @@ from typing import Optional
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import utm
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class UTMCoordinate:
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"""A GPS location represented in UTM coordinates.
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class Location:
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"""A location represented in WGS84 and UTM coordinates.
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For further info, we refer to this comprehensive article on the UTM system:
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https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
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WGS84:
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- "conventional" system with latitude-longitude pairs
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- assumes earth is a sphere and models the location in 3D
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UTM:
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- the Universal Transverse Mercator sytem
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- projects WGS84 coordinates onto a 2D map
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- can be used for visualizations and calculations directly
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- distances are in meters
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Further info how WGS84 and UTM are related:
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https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
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"""
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# pylint:disable=too-many-instance-attributes
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def __init__(
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self, latitude: float, longitude: float, relative_to: UTMCoordinate = None,
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) -> None:
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"""Cast a WGS84-conforming `latitude`-`longitude` pair as UTM coordinates."""
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def __init__(self, latitude: float, longitude: float) -> None:
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"""Create a location from a WGS84-conforming `latitude`-`longitude` pair."""
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# The SQLAlchemy columns come as `Decimal`s due to the `DOUBLE_PRECISION`.
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self._latitude = float(latitude)
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self._longitude = float(longitude)
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@ -35,36 +43,40 @@ class UTMCoordinate:
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self._normalized_easting: Optional[int] = None
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self._normalized_northing: Optional[int] = None
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if relative_to:
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try:
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self.relate_to(relative_to)
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except TypeError:
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raise TypeError(
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'`relative_to` must be a `UTMCoordinate` object',
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) from None
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except ValueError:
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raise ValueError(
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'`relative_to` must be in the same UTM zone as the `latitude`-`longitude` pair', # noqa:E501
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) from None
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def __repr__(self) -> str:
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"""A non-literal text representation.
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"""A non-literal text representation in the UTM system.
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Convention is {ZONE} {EASTING} {NORTHING}.
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Example:
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`<UTM: 17T 630084 4833438>'`
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`<Location: 17T 630084 4833438>'`
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"""
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return f'<UTM: {self.zone} {self.easting} {self.northing}>' # noqa:WPS221
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return f'<Location: {self.zone} {self.easting} {self.northing}>' # noqa:WPS221
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@property
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def latitude(self) -> float:
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"""The latitude of the location in degrees (WGS84).
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Between -90 and +90 degrees.
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"""
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return self._latitude
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@property
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def longitude(self) -> float:
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"""The longitude of the location in degrees (WGS84).
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Between -180 and +180 degrees.
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"""
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return self._longitude
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@property
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def easting(self) -> int:
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"""The easting of the location in meters."""
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"""The easting of the location in meters (UTM)."""
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return self._easting
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@property
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def northing(self) -> int:
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"""The northing of the location in meters."""
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"""The northing of the location in meters (UTM)."""
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return self._northing
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@property
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@ -73,8 +85,8 @@ class UTMCoordinate:
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return f'{self._zone}{self._band}'
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def __eq__(self, other: object) -> bool:
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"""Check if two `UTMCoordinate` objects are the same location."""
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if not isinstance(other, UTMCoordinate):
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"""Check if two `Location` objects are the same location."""
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if not isinstance(other, Location):
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return NotImplemented
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if self.zone != other.zone:
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@ -104,24 +116,21 @@ class UTMCoordinate:
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return self._normalized_northing
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def relate_to(self, other: UTMCoordinate) -> None:
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def relate_to(self, other: Location) -> None:
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"""Make the origin in the lower-left corner relative to `other`.
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The `.x` and `.y` properties are the `.easting` and `.northing` values
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of `self` minus the ones from `other`. So, `.x` and `.y` make up a
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Cartesian coordinate system where the `other` origin is `(0, 0)`.
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This method is implicitly called by `.__init__()` if that is called
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with a `relative_to` argument.
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To prevent semantic errors in calculations based on the `.x` and `.y`
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properties, the `other` origin may only be set once!
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"""
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if self._normalized_easting is not None:
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raise RuntimeError('the `other` origin may only be set once')
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if not isinstance(other, UTMCoordinate):
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raise TypeError('`other` is not a `UTMCoordinate` object')
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if not isinstance(other, Location):
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raise TypeError('`other` is not a `Location` object')
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if self.zone != other.zone:
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raise ValueError('`other` must be in the same zone, including the band')
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