def _proj4_str_to_dict(self, proj4_string):
"""
Converts PROJ4 compatible string to dictionary.
Parameters
----------
proj4_string : str
PROJ4 parameters as a string (e.g., '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs').
Returns
-------
dict
Dictionary containing PROJ4 parameters.
Notes
-----
Key only parameters will be assigned a value of `True`.
EPSG codes should be provided as "EPSG:XXXX" where "XXXX"
is the EPSG code number. It can also be provided as
"+init=EPSG:XXXX" as long as the underlying PROJ library
supports it (deprecated in PROJ 6.0+).
"""
# convert EPSG codes to equivalent PROJ4 string definition
if proj4_string.lower().startswith('epsg:'):
crs = CRS(proj4_string)
return crs.to_dict()
else:
proj4_pairs = (x.split('=', 1)
for x in proj4_string.replace('+', '').split(" "))
return self.__convert_proj4_pairs_to_dict(proj4_pairs)
def _convert_units(var,
name: str,
units: str,
p: Proj,
crs: CRS,
inverse: bool = False,
center=None):
"""Converts units from lon/lat to projection coordinates (meters).
If `inverse` it True then the inverse calculation is done.
"""
if var is None:
return None
if isinstance(var, DataArray):
units = var.units
var = tuple(var.data.tolist())
if crs.is_geographic and not ('deg' == units or 'degrees' == units):
raise ValueError(
'latlon/latlong projection cannot take {0} as units: {1}'.format(
units, name))
# Check if units are an angle.
is_angle = ('deg' == units or 'degrees' == units)
if ('deg' in units) and not is_angle:
logging.warning('units provided to {0} are incorrect: {1}'.format(
name, units))
# Convert from var projection units to projection units given by projection from user.
if not is_angle:
if units == 'meters' or units == 'metres':
units = 'm'
if _get_proj_units(crs) != units:
tmp_proj_dict = crs.to_dict()
tmp_proj_dict['units'] = units
transformer = Transformer.from_crs(tmp_proj_dict, p.crs)
var = transformer.transform(*var)
if name == 'center':
var = _round_poles(var, units, p)
# Return either degrees or meters depending on if the inverse is true or not.
# Don't convert if inverse is True: Want degrees.
# Converts list-like from degrees to meters.
if is_angle and not inverse:
if name in ('radius', 'resolution'):
var = _distance_from_center_forward(var, center, p)
elif not crs.is_geographic:
# only convert to meters
# this allows geographic projections to use coordinates outside
# normal lon/lat ranges (ex. -90/90)
var = p(*var, errcheck=True)
# Don't convert if inverse is False: Want meters.
elif not is_angle and inverse:
# Converts list-like from meters to degrees.
var = p(*var, inverse=True, errcheck=True)
if name in ['radius', 'resolution']:
var = (abs(var[0]), abs(var[1]))
return var
def proj4_radius_parameters(proj4_dict):
"""Calculate 'a' and 'b' radius parameters.
Arguments:
proj4_dict (str or dict): PROJ.4 parameters
Returns:
a (float), b (float): equatorial and polar radius
"""
if CRS is not None:
import math
crs = CRS(proj4_dict)
a = crs.ellipsoid.semi_major_metre
b = crs.ellipsoid.semi_minor_metre
if not math.isnan(b):
return a, b
# older versions of pyproj didn't always have a valid minor radius
proj4_dict = crs.to_dict()
if isinstance(proj4_dict, str):
new_info = proj4_str_to_dict(proj4_dict)
else:
new_info = proj4_dict.copy()
# load information from PROJ.4 about the ellipsis if possible
from pyproj import Geod
if 'ellps' in new_info:
geod = Geod(**new_info)
new_info['a'] = geod.a
new_info['b'] = geod.b
elif 'a' not in new_info or 'b' not in new_info:
if 'rf' in new_info and 'f' not in new_info:
new_info['f'] = 1. / float(new_info['rf'])
if 'a' in new_info and 'f' in new_info:
new_info['b'] = float(new_info['a']) * (1 - float(new_info['f']))
elif 'b' in new_info and 'f' in new_info:
new_info['a'] = float(new_info['b']) / (1 - float(new_info['f']))
elif 'R' in new_info:
new_info['a'] = new_info['R']
new_info['b'] = new_info['R']
else:
geod = Geod(**{'ellps': 'WGS84'})
new_info['a'] = geod.a
new_info['b'] = geod.b
return float(new_info['a']), float(new_info['b'])
def _proj4_str_to_dict(self, proj4_str):
"""Convert PROJ.4 compatible string definition to dict
EPSG codes should be provided as "EPSG:XXXX" where "XXXX"
is the EPSG number code. It can also be provided as
``"+init=EPSG:XXXX"`` as long as the underlying PROJ library
supports it (deprecated in PROJ 6.0+).
Note: Key only parameters will be assigned a value of `True`.
"""
# TODO: @shahn I would got for one solution, i.e. PyProj > 2.2
# TODO: test if this can be simplified
# # convert EPSG codes to equivalent PROJ4 string definition
if proj4_str.startswith('EPSG:'):
crs = CRS(proj4_str)
return crs.to_dict()
else:
proj4_pairs = (x.split('=', 1) for x in proj4_str.replace('+', '').split(" "))
return self.__convert_proj4_pairs_to_dict(proj4_pairs)
def proj4_str_to_dict(proj4_str):
"""Convert PROJ.4 compatible string definition to dict
EPSG codes should be provided as "EPSG:XXXX" where "XXXX"
is the EPSG number code. It can also be provided as
``"+init=EPSG:XXXX"`` as long as the underlying PROJ library
supports it (deprecated in PROJ 6.0+).
Note: Key only parameters will be assigned a value of `True`.
"""
# convert EPSG codes to equivalent PROJ4 string definition
if proj4_str.startswith('EPSG:') and CRS is not None:
crs = CRS(proj4_str)
if hasattr(crs, 'to_dict'):
# pyproj 2.2+
return crs.to_dict()
proj4_str = crs.to_proj4()
elif proj4_str.startswith('EPSG:'):
# legacy +init= PROJ4 string and no pyproj 2.0+ to help convert
proj4_str = "+init={}".format(proj4_str)
pairs = (x.split('=', 1) for x in proj4_str.replace('+', '').split(" "))
return convert_proj_floats(pairs)
