Implement from_namelist method

.github/workflows/ci.yaml

@@ -68,3 +68,26 @@ jobs:
       - name: Run Tests
         shell: bash -l {0}
         run: pytest --no-cov
+
+  bare-environment:
+    name: bare-environment
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: conda-incubator/setup-miniconda@v2
+        with:
+          environment-file: ci/bare-environment.yml
+          activate-environment: pydomcfg_test_bare
+          auto-update-conda: false
+          miniforge-variant: Mambaforge
+          use-mamba: true
+
+      - name: Set up conda environment
+        shell: bash -l {0}
+        run: |
+          python -m pip install -e .
+          conda list
+
+      - name: Run Tests
+        shell: bash -l {0}
+        run: pytest --no-cov

.pre-commit-config.yaml

@@ -41,7 +41,7 @@ repos:
     hooks:
       - id: mypy
         exclude: docs
-        additional_dependencies: [xarray, types-pkg_resources]
+        additional_dependencies: [xarray, types-pkg_resources, numpy!=1.21.0]
 
   - repo: https://github.com/PyCQA/doc8
     rev: 0.9.0a1

ci/bare-environment.yml

@@ -0,0 +1,9 @@
+name: pydomcfg_test_bare
+channels:
+  - conda-forge
+dependencies:
+  - pooch
+  - pytest-cov
+  - pytest
+  - pytest-xdist
+  - xarray

ci/environment.yml

@@ -7,3 +7,4 @@ dependencies:
   - pytest
   - pytest-xdist
   - xarray
+  - f90nml

ci/upstream-dev-env.yml

@@ -9,3 +9,4 @@ dependencies:
   - pip
   - pip:
     - git+https://github.com/pydata/xarray.git
+    - git+https://github.com/marshallward/f90nml.git

docs/developers/whats-new.rst

@@ -1,11 +1,13 @@
-.. currentmodule:: pydomcfg
+.. currentmodule:: xarray
 
 What's New
 ----------
 
 Unreleased
 ==========
 
+- Introduced :py:meth:`Dataset.domcfg.from_namelist` to use
+  ``NEMO DOMAINcfg`` namelists (:pr:`43`)
 - Introduced the ``domcfg`` accessor (:pr:`36`)
 - Added :py:meth:`~pydomcfg.tests.bathymetry.Bathymetry.sea_mount`
   useful to generate classic sea mount test case. (:pr:`17`)

docs/users/api.rst

@@ -21,6 +21,7 @@ Methods
    :toctree: generated/
    :template: autosummary/accessor_method.rst
 
+    Dataset.domcfg.from_namelist
     Dataset.domcfg.zco
 
 Domzgr

docs/users/installing.rst

@@ -9,6 +9,11 @@ Required dependencies
 - `xarray <http://xarray.pydata.org/>`_
 - `numpy <http://www.numpy.org/>`_
 
+Optional dependencies
+---------------------
+
+- `f90nml <https://f90nml.readthedocs.io/>`_
+
 Instructions
 ------------
 
@@ -18,5 +23,5 @@ The best way to install all dependencies is to use `conda <http://conda.io/>`_.
 
 .. code-block:: sh
 
-    conda install -c conda-forge xarray pip
+    conda install -c conda-forge xarray f90nml pip
     pip install git+https://github.com/pyNEMO/pyDOMCFG.git

pydomcfg/accessor.py

@@ -1,18 +1,36 @@
-from typing import Any, Callable, TypeVar, cast
+import inspect
+import warnings
+from collections import ChainMap
+from functools import wraps
+from pathlib import Path
+from typing import IO, Any, Callable, TypeVar, Union, cast
 
 import xarray as xr
 from xarray import Dataset
 
 from .domzgr.zco import Zco
 
+try:
+    import f90nml
+
+    HAS_F90NML = True
+except ImportError:
+    HAS_F90NML = False
+
 F = TypeVar("F", bound=Callable[..., Any])
+ZGR_MAPPER = {
+    "ln_zco": Zco,
+    # "ln_zps": TODO,
+    # "ln_sco": TODO
+}
 
 
 def _jpk_check(func: F) -> F:
     """
     Decorator to raise an error if jpk was not set
     """
 
+    @wraps(func)
     def wrapper(self, *args, **kwargs):
         if not self.jpk:
             raise ValueError(
@@ -29,7 +47,9 @@ class Accessor:
     def __init__(self, xarray_obj: Dataset):
         self._obj = xarray_obj
         self._jpk = 0
+        self._nml_ref_path = ""
 
+    # Set attributes
     @property
     def jpk(self) -> int:
         """
@@ -43,12 +63,112 @@ def jpk(self) -> int:
 
     @jpk.setter
     def jpk(self, value: int):
-        if value <= 0:
-            raise ValueError("`jpk` MUST be > 0")
+        if value < 0:
+            raise ValueError("`jpk` MUST be >= 0 (use 0 to unset jpk)")
         self._jpk = value
 
+    @property
+    def nml_ref_path(self) -> str:
+        """
+        Path to reference namelist.
+
+        Returns
+        -------
+        str
+        """
+        return self._nml_ref_path
+
+    @nml_ref_path.setter
+    def nml_ref_path(self, value: str):
+        self._nml_ref_path = value
+
+    # domzgr methods
+    # TODO:
+    #   I think the process of creating the public API and doc
+    #   can be further automatized, but let's not put too much effort into it
+    #   until we settle on the back-end structure:
+    #   See: https://github.com/pyNEMO/pyDOMCFG/issues/45
     @_jpk_check
     def zco(self, *args: Any, **kwargs: Any) -> Dataset:
-        return Zco(self._obj, self._jpk)(*args, **kwargs)
+        name = inspect.stack()[0][3]
+        return ZGR_MAPPER["ln_" + name](self._obj, self._jpk)(*args, **kwargs)
 
     zco.__doc__ = Zco.__call__.__doc__
+
+    # Emulate NEMO DOMAINcfg tools
+    def from_namelist(self, nml_cfg_path_or_io: Union[str, Path, IO[str]]) -> Dataset:
+        """
+        Auto-populate pydomcfg parameters using NEMO DOMAINcfg namelists.
+
+        Parameters
+        ----------
+        nml_cfg_path_or_io: str, Path, IO
+            Path pointing to a namelist_cfg,
+            or namelist_cfg previously opened with open()
+
+        Returns
+        -------
+        Dataset
+        """
+
+        nml_chained = self._namelist_parser(nml_cfg_path_or_io)
+        zgr_initialized, kwargs = self._get_zgr_initialized_and_kwargs(nml_chained)
+        return zgr_initialized(**kwargs)
+
+    def _namelist_parser(
+        self, nml_cfg_path_or_io: Union[str, Path, IO[str]]
+    ) -> ChainMap:
+        """Parse namelists using f90nml, chaining all namblocks"""
+
+        if not HAS_F90NML:
+            raise ImportError(
+                "`f90nml` MUST be installed to use `obj.domcfg.from_namelist()`"
+            )
+
+        if not self.nml_ref_path:
+            raise ValueError(
+                "Set `nml_ref_path` before calling `obj.domcfg.from_namelist()`"
+                " For example: obj.domcfg.nml_ref_path = 'path/to/nml_ref'"
+            )
+
+        if self.jpk:
+            warnings.warn(
+                "`obj.domcfg.jpk` is ignored. `jpk` is inferred from the namelists."
+            )
+
+        # Read namelists: cfg overrides ref
+        nml_cfg = f90nml.read(nml_cfg_path_or_io)
+        nml = f90nml.patch(self.nml_ref_path, nml_cfg)
+
+        return ChainMap(*nml.todict().values())
+
+    def _get_zgr_initialized_and_kwargs(self, nml_chained: ChainMap):
+
+        # TODO: Add return type hint when abstraction in base class is implemented
+
+        # Pick the appropriate class
+        zgr_classes = [
+            value for key, value in ZGR_MAPPER.items() if nml_chained.get(key)
+        ]
+        if len(zgr_classes) != 1:
+            raise ValueError(
+                "One and only one of the following variables MUST be `.true.`:"
+                f" {tuple(ZGR_MAPPER)}"
+            )
+        zgr_class = zgr_classes[0]
+
+        # Compatibility with NEMO DOMAINcfg
+        if nml_chained.get("ldbletanh") is False:
+            for pp in ["ppa2", "ppkth2", "ppacr2"]:
+                nml_chained[pp] = None
+
+        # Get kwargs, converting 999_999 to None
+        parameters = list(inspect.signature(zgr_class.__call__).parameters)
+        parameters.remove("self")
+        kwargs = {
+            key: None if nml_chained[key] == 999_999 else nml_chained[key]
+            for key in parameters
+            if key in nml_chained
+        }
+
+        return zgr_class(self._obj, nml_chained["jpkdta"]), kwargs