Use PyProj instead of Cartopy for internal coordinate transforms and rename crs coordinate

.github/workflows/docs.yml

@@ -98,7 +98,7 @@ jobs:
 
     - name: Enable linkchecker for PRs
       if: ${{ github.event_name == 'pull_request' && matrix.check-links == true }}
-      run: echo "::set-env name=LINKCHECKER::linkcheck"
+      run: echo "LINKCHECKER=linkcheck" >> $GITHUB_ENV
 
     - name: Build docs
       run: |
@@ -120,7 +120,7 @@ jobs:
     # branch that's not master (which is confined to n.nn.x above) or on a tag.
     - name: Set doc version
       if: ${{ github.event_name != 'push' || !contains(github.ref, 'master') }}
-      run: echo "::set-env name=DOC_VERSION::v$(python -c 'import metpy; print(metpy.__version__.rsplit(".", maxsplit=2)[0])')"
+      run: echo "DOC_VERSION=v$(python -c 'import metpy; print(metpy.__version__.rsplit(".", maxsplit=2)[0])')" >> $GITHUB_ENV
 
     - name: Upload to GitHub Pages
       if: ${{ github.event_name != 'pull_request' && matrix.experimental == false }}

.github/workflows/linting.yml

@@ -25,7 +25,7 @@ jobs:
           curl -sfL \
             https://github.com/reviewdog/reviewdog/raw/master/install.sh | \
               sh -s -- -b $HOME/bin
-          echo ::add-path::$HOME/bin
+          echo "$HOME/bin" >> $GITHUB_PATH
 
       - name: Run flake8
         env:

.github/workflows/tests-conda.yml

@@ -108,6 +108,7 @@ jobs:
         path: test_output/
 
     - name: Upload coverage
+      if: ${{ always() }}
       uses: codecov/codecov-action@v1
       with:
         name: conda-${{ matrix.python-version }}-${{ runner.os }}

.github/workflows/tests-pypi.yml

@@ -126,6 +126,7 @@ jobs:
         path: test_output/
 
     - name: Upload coverage
+      if: ${{ always() }}
       uses: codecov/codecov-action@v1
       with:
         name: pypi-${{ matrix.python-version }}-${{ matrix.dep-versions }}-${{ matrix.no-extras }}-${{ runner.os }}

.travis.yml

@@ -88,7 +88,7 @@ script:
     fi
 
 after_script:
-  - if [[ $TASK != "coverage" ]]; then
+  - if [[ $TASK == "coverage" ]]; then
       pip install codecov codacy-coverage;
       coverage xml;
       codecov -X gcov -f coverage.xml -e TRAVIS_PYTHON_VERSION;

ci/Current.txt

@@ -1,10 +1,11 @@
+importlib_metadata==2.0.0
+importlib_resources==3.0.0
 matplotlib==3.3.2
 numpy==1.19.1
-scipy==1.5.2
+pandas==1.1.3
+pooch==1.2.0
 pint==0.16.1
-xarray==0.16.1
+pyproj==2.6.1.post1
+scipy==1.5.2
 traitlets==4.3.3
-pooch==1.2.0
-pandas==1.1.3
-importlib_metadata==2.0.0
-importlib_resources==3.0.0
+xarray==0.16.1

ci/Minimum

@@ -1,10 +1,11 @@
+importlib_metadata==1.0.0
+importlib_resources==1.3.0
 matplotlib==2.1.0
 numpy==1.16.0
-scipy==1.0.0
+pandas==0.22.0
 pint==0.10.1
-xarray==0.14.1
-traitlets==4.3.0
 pooch==0.1
-pandas==0.22.0
-importlib_metadata==1.0.0
-importlib_resources==1.3.0
+pyproj==2.3.0
+scipy==1.0.0
+traitlets==4.3.0
+xarray==0.14.1

ci/Prerelease

@@ -1,6 +1,7 @@
 matplotlib>=0.0.dev0
 numpy>=0.0.dev0
-scipy>=0.0.dev0
-traitlets>=0.0.dev0
 pooch>=0.0.dev0
 pandas>=0.0.dev0
+pyproj>=0.0.dev0
+scipy>=0.0.dev0
+traitlets>=0.0.dev0

ci/extra_requirements.txt

@@ -1,2 +1 @@
 cartopy==0.18.0
-pyproj==2.6.1.post1

conftest.py

@@ -10,6 +10,7 @@
 import numpy
 import pandas
 import pooch
+import pyproj
 import pytest
 import scipy
 import traitlets
@@ -25,10 +26,10 @@
 def pytest_report_header(config, startdir):
     """Add dependency information to pytest output."""
     return (f'Dep Versions: Matplotlib {matplotlib.__version__}, '
-            f'NumPy {numpy.__version__}, SciPy {scipy.__version__}, '
-            f'Xarray {xarray.__version__}, Pint {pint.__version__}, '
-            f'Pandas {pandas.__version__}, Traitlets {traitlets.__version__}, '
-            f'Pooch {pooch.version.full_version}')
+            f'NumPy {numpy.__version__}, Pandas {pandas.__version__}, '
+            f'Pint {pint.__version__}, Pooch {pooch.version.full_version}\n'
+            f'\tPyProj {pyproj.__version__}, SciPy {scipy.__version__}, '
+            f'Traitlets {traitlets.__version__}, Xarray {xarray.__version__}')
 
 
 @pytest.fixture(autouse=True)
@@ -45,6 +46,7 @@ def ccrs():
 
     Any testing function/fixture that needs access to ``cartopy.crs`` can simply add this to
     their parameter list.
+
     """
     return pytest.importorskip('cartopy.crs')
 
@@ -55,15 +57,14 @@ def cfeature():
 
     Any testing function/fixture that needs access to ``cartopy.feature`` can simply add this
     to their parameter list.
+
     """
     return pytest.importorskip('cartopy.feature')
 
 
 @pytest.fixture()
 def test_da_lonlat():
     """Return a DataArray with a lon/lat grid and no time coordinate for use in tests."""
-    pytest.importorskip('cartopy')
-
     data = numpy.linspace(300, 250, 3 * 4 * 4).reshape((3, 4, 4))
     ds = xarray.Dataset(
         {'temperature': (['isobaric', 'lat', 'lon'], data)},
@@ -96,8 +97,6 @@ def test_da_lonlat():
 @pytest.fixture()
 def test_da_xy():
     """Return a DataArray with a x/y grid and a time coordinate for use in tests."""
-    pytest.importorskip('cartopy')
-
     data = numpy.linspace(300, 250, 3 * 3 * 4 * 4).reshape((3, 3, 4, 4))
     ds = xarray.Dataset(
         {'temperature': (['time', 'isobaric', 'y', 'x'], data),

docs/installguide.rst

@@ -10,12 +10,13 @@ years. For Python itself, that means supporting the last two minor releases.
 
 * matplotlib >= 2.1.0
 * numpy >= 1.16.0
-* scipy >= 1.0.0
-* pint >= 0.10.1
 * pandas >= 0.22.0
-* xarray >= 0.14.1
-* traitlets >= 4.3.0
+* pint >= 0.10.1
 * pooch >= 0.1
+* pyproj >= 2.3.0
+* scipy >= 1.0.0
+* traitlets >= 4.3.0
+* xarray >= 0.14.1
 
 ------------
 Installation

setup.cfg

@@ -39,16 +39,17 @@ include_package_data = True
 setup_requires = setuptools_scm
 python_requires = >=3.6
 install_requires =
+    importlib_metadata>=1.0.0; python_version < '3.8'
+    importlib_resources>=1.3.0; python_version < '3.9'
     matplotlib>=2.1.0
     numpy>=1.16.0
-    scipy>=1.0
+    pandas>=0.22.0
     pint>=0.10.1
-    xarray>=0.14.1
     pooch>=0.1
+    pyproj>=2.3.0,<3.0
+    scipy>=1.0
     traitlets>=4.3.0
-    pandas>=0.22.0
-    importlib_metadata>=1.0.0; python_version < '3.8'
-    importlib_resources>=1.3.0; python_version < '3.9'
+    xarray>=0.14.1
 
 [options.packages.find]
 where = src

src/metpy/calc/cross_sections.py

@@ -36,9 +36,7 @@ def distances_from_cross_section(cross):
     """
     if check_axis(cross.metpy.x, 'longitude') and check_axis(cross.metpy.y, 'latitude'):
         # Use pyproj to obtain x and y distances
-        from pyproj import Geod
-
-        g = Geod(cross.metpy.cartopy_crs.proj4_init)
+        g = cross.metpy.pyproj_crs.get_geod()
         lon = cross.metpy.x
         lat = cross.metpy.y
 
@@ -83,10 +81,13 @@ def latitude_from_cross_section(cross):
     if check_axis(y, 'latitude'):
         return y
     else:
-        import cartopy.crs as ccrs
-        latitude = ccrs.Geodetic().transform_points(cross.metpy.cartopy_crs,
-                                                    cross.metpy.x.values,
-                                                    y.values)[..., 1]
+        from pyproj import Proj
+        latitude = Proj(cross.metpy.pyproj_crs)(
+            cross.metpy.x.values,
+            y.values,
+            inverse=True,
+            radians=False
+        )[1]
         latitude = xr.DataArray(latitude * units.degrees_north, coords=y.coords, dims=y.dims)
         return latitude
 

src/metpy/calc/tools.py

@@ -8,6 +8,7 @@
 import numpy as np
 from numpy.core.numeric import normalize_axis_index
 import numpy.ma as ma
+from pyproj import Geod
 from scipy.spatial import cKDTree
 import xarray as xr
 
@@ -763,7 +764,7 @@ def take(indexer):
 
 @exporter.export
 @preprocess_and_wrap()
-def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, **kwargs):
+def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, geod=None):
     r"""Calculate the actual delta between grid points that are in latitude/longitude format.
 
     Parameters
@@ -778,8 +779,9 @@ def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, **kwargs):
         axis number for the x dimension, defaults to -1.
     y_dim : int
         axis number for the y dimesion, defaults to -2.
-    kwargs
-        Other keyword arguments to pass to :class:`~pyproj.Geod`
+    geod : `pyproj.Geod` or ``None``
+        PyProj Geod to use for forward azimuth and distance calculations. If ``None``, use a
+        default spherical ellipsoid.
 
     Returns
     -------
@@ -797,8 +799,6 @@ def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, **kwargs):
     array-like type). It will also "densify" your data if using Dask or lazy-loading.
 
     """
-    from pyproj import Geod
-
     # Inputs must be the same number of dimensions
     if latitude.ndim != longitude.ndim:
         raise ValueError('Latitude and longitude must have the same number of dimensions.')
@@ -819,11 +819,10 @@ def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, **kwargs):
     take_y = make_take(latitude.ndim, y_dim)
     take_x = make_take(latitude.ndim, x_dim)
 
-    geod_args = {'ellps': 'sphere'}
-    if kwargs:
-        geod_args = kwargs
-
-    g = Geod(**geod_args)
+    if geod is None:
+        g = Geod(ellps='sphere')
+    else:
+        g = geod
 
     forward_az, _, dy = g.inv(longitude[take_y(slice(None, -1))],
                               latitude[take_y(slice(None, -1))],
@@ -842,7 +841,7 @@ def lat_lon_grid_deltas(longitude, latitude, x_dim=-1, y_dim=-2, **kwargs):
 
 @exporter.export
 @preprocess_and_wrap()
-def azimuth_range_to_lat_lon(azimuths, ranges, center_lon, center_lat, **kwargs):
+def azimuth_range_to_lat_lon(azimuths, ranges, center_lon, center_lat, geod=None):
     """Convert azimuth and range locations in a polar coordinate system to lat/lon coordinates.
 
     Pole refers to the origin of the coordinate system.
@@ -858,8 +857,9 @@ def azimuth_range_to_lat_lon(azimuths, ranges, center_lon, center_lat, **kwargs)
         The latitude of the pole in decimal degrees
     center_lon : float
         The longitude of the pole in decimal degrees
-    kwargs
-        arbitrary keyword arguments to pass to pyproj.Geod (e.g. 'ellps')
+    geod : `pyproj.Geod` or ``None``
+        PyProj Geod to use for forward azimuth and distance calculations. If ``None``, use a
+        default spherical ellipsoid.
 
     Returns
     -------
@@ -870,12 +870,10 @@ def azimuth_range_to_lat_lon(azimuths, ranges, center_lon, center_lat, **kwargs)
     Credit to Brian Blaylock for the original implementation.
 
     """
-    from pyproj import Geod
-
-    geod_args = {'ellps': 'sphere'}
-    if kwargs:
-        geod_args = kwargs
-    g = Geod(**geod_args)
+    if geod is None:
+        g = Geod(ellps='sphere')
+    else:
+        g = geod
 
     rng2d, az2d = np.meshgrid(ranges, azimuths)
     lats = np.full(az2d.shape, center_lat)

src/metpy/interpolate/slices.py

@@ -74,8 +74,8 @@ def geodesic(crs, start, end, steps):
 
     Parameters
     ----------
-    crs: `cartopy.crs`
-        Cartopy Coordinate Reference System to use for the output
+    crs: `pyproj.CRS`
+        PyProj Coordinate Reference System to use for the output
     start: (2, ) array_like
         A latitude-longitude pair designating the start point of the geodesic (units are
         degrees north and degrees east).
@@ -96,18 +96,19 @@ def geodesic(crs, start, end, steps):
     cross_section
 
     """
-    import cartopy.crs as ccrs
-    from pyproj import Geod
+    from pyproj import Proj
+
+    g = crs.get_geod()
+    p = Proj(crs)
 
     # Geod.npts only gives points *in between* the start and end, and we want to include
     # the endpoints.
-    g = Geod(crs.proj4_init)
     geodesic = np.concatenate([
         np.array(start[::-1])[None],
         np.array(g.npts(start[1], start[0], end[1], end[0], steps - 2)),
         np.array(end[::-1])[None]
     ]).transpose()
-    points = crs.transform_points(ccrs.Geodetic(), *geodesic)[:, :2]
+    points = np.stack(p(geodesic[0], geodesic[1], inverse=False, radians=False), axis=-1)
 
     return points
 
@@ -162,7 +163,7 @@ def cross_section(data, start, end, steps=100, interp_type='linear'):
 
         # Get the projection and coordinates
         try:
-            crs_data = data.metpy.cartopy_crs
+            crs_data = data.metpy.pyproj_crs
             x = data.metpy.x
         except AttributeError:
             raise ValueError('Data missing required coordinate information. Verify that '

src/metpy/plots/mapping.py

@@ -77,6 +77,12 @@ def to_cartopy(self):
 
         return proj_handler(self._attrs, globe)
 
+    def to_pyproj(self):
+        """Convert to a PyProj CRS."""
+        import pyproj
+
+        return pyproj.CRS.from_cf(self._attrs)
+
     def to_dict(self):
         """Get the dictionary of metadata attributes."""
         return self._attrs.copy()

src/metpy/testing.py

@@ -34,19 +34,6 @@ def wrapped(*args, **kwargs):
     return wrapped
 
 
-def needs_pyproj(test_func):
-    """Decorate a test function or fixture as requiring PyProj.
-
-    Will skip the decorated test, or any test using the decorated fixture, if ``pyproj`` is
-    unable to be imported.
-    """
-    @functools.wraps(test_func)
-    def wrapped(*args, **kwargs):
-        pytest.importorskip('pyproj')
-        return test_func(*args, **kwargs)
-    return wrapped
-
-
 def get_upper_air_data(date, station):
     """Get upper air observations from the test data cache.