Transformer with MercatorAConversion with lat/lon of natural origin returns ProjError

latlon_crs = CRS("EPSG:4326")
conv = MercatorAConversion(latitude_natural_origin=0.1, longitude_natural_origin=0.1)
merc_crs = ProjectedCRS(conversion=conv)
transform_func = Transformer.from_crs(latlon_crs, merc_crs, always_xy=True).transform

Problem description

The above code returns ProjError: Input is not a transformation. If latitude_natural_origin=0 and longitude_natural_origin=0, no error is returned.

Expected Output

No error.

Environment Information

• Output from: pyproj -v

pyproj info:
    pyproj: 3.3.1
      PROJ: 9.0.0
  data dir: /Users/kpenner/dev/pyproj/share/proj
user_data_dir: /Users/kpenner/Library/Application Support/proj
PROJ DATA (recommended version): 1.9
PROJ Database: 1.2
EPSG Database: v10.054 [2022-02-13]
ESRI Database: ArcMap 12.9 [2022-02-18]
IGNF Database: 3.1.0 [2019-05-24]

System:
    python: 3.10.4 | packaged by conda-forge | (main, Mar 24 2022, 17:45:10) [Clang 12.0.1 ]
executable: /Users/kpenner/dev/pyproj/bin/python
   machine: macOS-12.4-x86_64-i386-64bit

Python deps:
/Users/kpenner/dev/pyproj/lib/python3.10/site-packages/_distutils_hack/__init__.py:30: UserWarning: Setuptools is replacing distutils.
  warnings.warn("Setuptools is replacing distutils.")
   certifi: 2022.05.18.1
    Cython: None
setuptools: 62.3.2
       pip: 22.1.2

Installation method

• conda

Conda environment information

Environment (conda list):

# Name                    Version                   Build  Channel
proj                      9.0.0                h2364a93_1    conda-forge
pyproj                    3.3.1           py310h6c09501_0    conda-forge

Details about conda and system ( conda info ):

     active environment : pyproj
    active env location : /Users/kpenner/dev/pyproj
            shell level : 2
       user config file : /Users/kpenner/.condarc
 populated config files : /Users/kpenner/.condarc
          conda version : 4.12.0
    conda-build version : not installed
         python version : 3.7.12.final.0
       virtual packages : __osx=10.16=0
                          __unix=0=0
                          __archspec=1=x86_64
       base environment : /Users/kpenner/miniconda3  (writable)
      conda av data dir : /Users/kpenner/miniconda3/etc/conda
  conda av metadata url : None
           channel URLs : https://conda.anaconda.org/conda-forge/osx-64
                          https://conda.anaconda.org/conda-forge/noarch
                          https://repo.anaconda.com/pkgs/main/osx-64
                          https://repo.anaconda.com/pkgs/main/noarch
                          https://repo.anaconda.com/pkgs/r/osx-64
                          https://repo.anaconda.com/pkgs/r/noarch
          package cache : /Users/kpenner/miniconda3/pkgs
                          /Users/kpenner/.conda/pkgs
       envs directories : /Users/kpenner/dev
                          /Users/kpenner/miniconda3/envs
                          /Users/kpenner/.conda/envs
               platform : osx-64
             user-agent : conda/4.12.0 requests/2.27.1 CPython/3.7.12 Darwin/21.5.0 OSX/10.16
                UID:GID : 501:20
             netrc file : None
           offline mode : False

[snowman2]

What’s the reason for keeping latitude_natural_origin as a kwarg if only 0 is supported?

For completeness sake when creating CRS and exporting to WKT. This may be needed even if PROJ does not support it for transformations.

On an unrelated note, the lat_ts PROJ parameter is unsupported by pyproj.

See MercatorBConversion

[snowman2]

Happy to submit a PR soon. Should a warning be raised if a non-zero latitude_natural_origin is passed?

Thanks! I am thinking since it is invalid, a CRSError should be raised in the initialization around here.