"""
Performs cartographic transformations (converts from
longitude,latitude to native map projection x,y coordinates and
vice versa) using PROJ (https://proj.org).
A Proj class instance is initialized with proj map projection
control parameter key/value pairs. The key/value pairs can
either be passed in a dictionary, or as keyword arguments,
or as a PROJ string (compatible with the proj command). See
:ref:`projections` for examples of
key/value pairs defining different map projections.
Calling a Proj class instance with the arguments lon, lat will
convert lon/lat (in degrees) to x/y native map projection
coordinates (in meters).
"""
import re
import warnings
from typing import Any, Optional
from pyproj._compat import cstrencode
from pyproj._transformer import Factors
from pyproj.crs import CRS
from pyproj.enums import TransformDirection
from pyproj.list import get_proj_operations_map
from pyproj.transformer import Transformer, TransformerFromPipeline
from pyproj.utils import _convertback, _copytobuffer
pj_list = get_proj_operations_map()
[docs]
class Proj(Transformer):
"""
Performs cartographic transformations. Converts from
longitude, latitude to native map projection x,y coordinates and
vice versa using PROJ (https://proj.org).
Attributes
----------
srs: str
The string form of the user input used to create the Proj.
crs: pyproj.crs.CRS
The CRS object associated with the Proj.
"""
[docs]
def __init__(
self, projparams: Optional[Any] = None, preserve_units: bool = True, **kwargs
) -> None:
"""
A Proj class instance is initialized with proj map projection
control parameter key/value pairs. The key/value pairs can
either be passed in a dictionary, or as keyword arguments,
or as a PROJ string (compatible with the proj command). See
:ref:`projections` for examples of
key/value pairs defining different map projections.
Parameters
----------
projparams: int, str, dict, pyproj.CRS
A PROJ or WKT string, PROJ dict, EPSG integer, or a pyproj.CRS instance.
preserve_units: bool
If false, will ensure +units=m.
**kwargs:
PROJ projection parameters.
Example usage:
>>> from pyproj import Proj
>>> p = Proj(proj='utm',zone=10,ellps='WGS84', preserve_units=False)
>>> x,y = p(-120.108, 34.36116666)
>>> 'x=%9.3f y=%11.3f' % (x,y)
'x=765975.641 y=3805993.134'
>>> 'lon=%8.3f lat=%5.3f' % p(x,y,inverse=True)
'lon=-120.108 lat=34.361'
>>> # do 3 cities at a time in a tuple (Fresno, LA, SF)
>>> lons = (-119.72,-118.40,-122.38)
>>> lats = (36.77, 33.93, 37.62 )
>>> x,y = p(lons, lats)
>>> 'x: %9.3f %9.3f %9.3f' % x
'x: 792763.863 925321.537 554714.301'
>>> 'y: %9.3f %9.3f %9.3f' % y
'y: 4074377.617 3763936.941 4163835.303'
>>> lons, lats = p(x, y, inverse=True) # inverse transform
>>> 'lons: %8.3f %8.3f %8.3f' % lons
'lons: -119.720 -118.400 -122.380'
>>> 'lats: %8.3f %8.3f %8.3f' % lats
'lats: 36.770 33.930 37.620'
>>> p2 = Proj('+proj=utm +zone=10 +ellps=WGS84', preserve_units=False)
>>> x,y = p2(-120.108, 34.36116666)
>>> 'x=%9.3f y=%11.3f' % (x,y)
'x=765975.641 y=3805993.134'
>>> p = Proj("EPSG:32667", preserve_units=False)
>>> 'x=%12.3f y=%12.3f (meters)' % p(-114.057222, 51.045)
'x=-1783506.250 y= 6193827.033 (meters)'
>>> p = Proj("EPSG:32667")
>>> 'x=%12.3f y=%12.3f (feet)' % p(-114.057222, 51.045)
'x=-5851386.754 y=20320914.191 (feet)'
>>> # test data with radian inputs
>>> p1 = Proj("EPSG:4214")
>>> x1, y1 = p1(116.366, 39.867)
>>> f'{x1:.3f} {y1:.3f}'
'116.366 39.867'
>>> x2, y2 = p1(x1, y1, inverse=True)
>>> f'{x2:.3f} {y2:.3f}'
'116.366 39.867'
"""
self.crs = CRS.from_user_input(projparams, **kwargs)
# make sure units are meters if preserve_units is False.
if not preserve_units and "foot" in self.crs.axis_info[0].unit_name:
# ignore export to PROJ string deprecation warning
with warnings.catch_warnings():
warnings.filterwarnings(
"ignore",
"You will likely lose important projection information",
UserWarning,
)
projstring = self.crs.to_proj4(4)
projstring = re.sub(r"\s\+units=[\w-]+", "", projstring)
projstring += " +units=m"
self.crs = CRS(projstring)
# ignore export to PROJ string deprecation warning
with warnings.catch_warnings():
warnings.filterwarnings(
"ignore",
"You will likely lose important projection information",
UserWarning,
)
projstring = self.crs.to_proj4() or self.crs.srs
self.srs = re.sub(r"\s\+?type=crs", "", projstring).strip()
super().__init__(TransformerFromPipeline(cstrencode(self.srs)))
[docs]
def __call__(
self,
longitude: Any,
latitude: Any,
inverse: bool = False,
errcheck: bool = False,
radians: bool = False,
) -> tuple[Any, Any]:
"""
Calling a Proj class instance with the arguments lon, lat will
convert lon/lat (in degrees) to x/y native map projection
coordinates (in meters).
Inputs should be doubles (they will be cast to doubles if they
are not, causing a slight performance hit).
Works with numpy and regular python array objects, python
sequences and scalars, but is fastest for array objects.
Accepted numeric scalar or array:
- :class:`int`
- :class:`float`
- :class:`numpy.floating`
- :class:`numpy.integer`
- :class:`list`
- :class:`tuple`
- :class:`array.array`
- :class:`numpy.ndarray`
- :class:`xarray.DataArray`
- :class:`pandas.Series`
Parameters
----------
longitude: scalar or array
Input longitude coordinate(s).
latitude: scalar or array
Input latitude coordinate(s).
inverse: bool, default=False
If inverse is True the inverse transformation from x/y to
lon/lat is performed.
radians: bool, default=False
If True, will expect input data to be in radians and will return radians
if the projection is geographic. Otherwise, it uses degrees.
This does not work with pyproj 2 and is ignored. It will be enabled again
in pyproj 3.
errcheck: bool, default=False
If True, an exception is raised if the errors are found in the process.
If False, ``inf`` is returned for errors.
Returns
-------
tuple[Any, Any]:
The transformed coordinates.
"""
if inverse:
direction = TransformDirection.INVERSE
else:
direction = TransformDirection.FORWARD
return self.transform(
xx=longitude,
yy=latitude,
direction=direction,
errcheck=errcheck,
radians=radians,
)
[docs]
def get_factors(
self,
longitude: Any,
latitude: Any,
radians: bool = False,
errcheck: bool = False,
) -> Factors:
"""
.. versionadded:: 2.6.0
Calculate various cartographic properties, such as scale factors, angular
distortion and meridian convergence. Depending on the underlying projection
values will be calculated either numerically (default) or analytically.
The function also calculates the partial derivatives of the given
coordinate.
Accepted numeric scalar or array:
- :class:`int`
- :class:`float`
- :class:`numpy.floating`
- :class:`numpy.integer`
- :class:`list`
- :class:`tuple`
- :class:`array.array`
- :class:`numpy.ndarray`
- :class:`xarray.DataArray`
- :class:`pandas.Series`
Parameters
----------
longitude: scalar or array
Input longitude coordinate(s).
latitude: scalar or array
Input latitude coordinate(s).
radians: bool, default=False
If True, will expect input data to be in radians and will return radians
if the projection is geographic. Otherwise, it uses degrees.
errcheck: bool, default=False
If True, an exception is raised if the errors are found in the process.
If False, ``inf`` is returned on error.
Returns
-------
Factors
"""
# process inputs, making copies that support buffer API.
inx, x_data_type = _copytobuffer(longitude)
iny = _copytobuffer(latitude)[0]
# calculate the factors
factors = self._transformer._get_factors(
inx, iny, radians=radians, errcheck=errcheck
)
# if inputs were lists, tuples or floats, convert back.
return Factors(
meridional_scale=_convertback(x_data_type, factors.meridional_scale),
parallel_scale=_convertback(x_data_type, factors.parallel_scale),
areal_scale=_convertback(x_data_type, factors.areal_scale),
angular_distortion=_convertback(x_data_type, factors.angular_distortion),
meridian_parallel_angle=_convertback(
x_data_type, factors.meridian_parallel_angle
),
meridian_convergence=_convertback(
x_data_type, factors.meridian_convergence
),
tissot_semimajor=_convertback(x_data_type, factors.tissot_semimajor),
tissot_semiminor=_convertback(x_data_type, factors.tissot_semiminor),
dx_dlam=_convertback(x_data_type, factors.dx_dlam),
dx_dphi=_convertback(x_data_type, factors.dx_dphi),
dy_dlam=_convertback(x_data_type, factors.dy_dlam),
dy_dphi=_convertback(x_data_type, factors.dy_dphi),
)
[docs]
def definition_string(self) -> str:
"""Returns formal definition string for projection
>>> Proj("EPSG:4326").definition_string()
'proj=longlat datum=WGS84 no_defs ellps=WGS84 towgs84=0,0,0'
"""
return self.definition
[docs]
def to_latlong_def(self) -> Optional[str]:
"""return the definition string of the geographic (lat/lon)
coordinate version of the current projection"""
return self.crs.geodetic_crs.to_proj4(4) if self.crs.geodetic_crs else None
[docs]
def to_latlong(self) -> "Proj":
"""return a new Proj instance which is the geographic (lat/lon)
coordinate version of the current projection"""
return Proj(self.crs.geodetic_crs)
def __reduce__(self) -> tuple[type["Proj"], tuple[str]]:
"""special method that allows pyproj.Proj instance to be pickled"""
return self.__class__, (self.crs.srs,)