ruff compliance for D401.

.ruff.toml

@@ -29,7 +29,6 @@ lint.ignore = [
     "D102",  # Missing docstring in public method
     # (D-3) Temporary, before an initial review, either fix ocurrences or move to (2).
     "D103",  # Missing docstring in public function
-    "D401",  # First line of docstring should be in imperative mood: ...
 
     # pyupgrade (UP)
     # https://docs.astral.sh/ruff/rules/#pyupgrade-up

benchmarks/benchmarks/__init__.py

@@ -10,7 +10,7 @@
 
 
 def disable_repeat_between_setup(benchmark_object):
-    """Decorator for benchmarks where object persistence would be inappropriate.
+    """Benchmarks where object persistence would be inappropriate (decorator).
 
     E.g:
         * Benchmarking data realisation
@@ -86,7 +86,7 @@ def addedmem_mb(self):
 
     @staticmethod
     def decorator(decorated_func):
-        """Decorates this benchmark to track growth in resident memory during execution.
+        """Benchmark to track growth in resident memory during execution.
 
         Intended for use on ASV ``track_`` benchmarks. Applies the
         :class:`TrackAddedMemoryAllocation` context manager to the benchmark
@@ -107,7 +107,9 @@ def _wrapper(*args, **kwargs):
 
 
 def on_demand_benchmark(benchmark_object):
-    """Decorator. Disables these benchmark(s) unless ON_DEMAND_BENCHARKS env var is set.
+    """Disables these benchmark(s) unless ON_DEMAND_BENCHARKS env var is set.
+
+    This is a decorator.
 
     For benchmarks that, for whatever reason, should not be run by default.
     E.g:

benchmarks/benchmarks/cperf/load.py

@@ -10,7 +10,7 @@
 @on_demand_benchmark
 class SingleDiagnosticLoad(SingleDiagnosticMixin):
     def time_load(self, _, __, ___):
-        """The 'real world comparison'.
+        """Perform a 'real world comparison'.
 
         * UM coords are always realised (DimCoords).
         * LFRic coords are not realised by default (MeshCoords).
@@ -26,7 +26,7 @@ def time_load(self, _, __, ___):
             assert coord.has_lazy_bounds() == expecting_lazy_coords
 
     def time_load_w_realised_coords(self, _, __, ___):
-        """A valuable extra comparison where both UM and LFRic coords are realised."""
+        """Valuable extra comparison where both UM and LFRic coords are realised."""
         cube = self.load()
         for coord_name in "longitude", "latitude":
             coord = cube.coord(coord_name)

benchmarks/benchmarks/cube.py

@@ -45,7 +45,7 @@ def setup(self):
         raise NotImplementedError
 
     def create(self):
-        """Generic cube creation.
+        """Create a cube (generic).
 
         cube_kwargs allow dynamic inclusion of different components;
         specified in subclasses.

benchmarks/benchmarks/experimental/ugrid/regions_combine.py

@@ -92,7 +92,7 @@ def setup_cache(self):
             )
 
     def setup(self, n_cubesphere, imaginary_data=True, create_result_cube=True):
-        """The combine-tests "standard" setup operation.
+        """Combine-tests "standard" setup operation.
 
         Load the source cubes (full-mesh + region) from disk.
         These are specific to the cubesize parameter.

benchmarks/benchmarks/generate_data/stock.py

@@ -49,7 +49,7 @@ def _external(func_name_, temp_file_dir, **kwargs_):
 def create_file__xios_2d_face_half_levels(
     temp_file_dir, dataset_name, n_faces=866, n_times=1
 ):
-    """Wrapper for :meth:`iris.tests.stock.netcdf.create_file__xios_2d_face_half_levels`.
+    """Create file wrapper for :meth:`iris.tests.stock.netcdf.create_file__xios_2d_face_half_levels`.
 
     Have taken control of temp_file_dir
 
@@ -67,7 +67,7 @@ def create_file__xios_2d_face_half_levels(
 def create_file__xios_3d_face_half_levels(
     temp_file_dir, dataset_name, n_faces=866, n_times=1, n_levels=38
 ):
-    """Wrapper for :meth:`iris.tests.stock.netcdf.create_file__xios_3d_face_half_levels`.
+    """Create file wrapper for :meth:`iris.tests.stock.netcdf.create_file__xios_3d_face_half_levels`.
 
     Have taken control of temp_file_dir
 
@@ -84,7 +84,7 @@ def create_file__xios_3d_face_half_levels(
 
 
 def sample_mesh(n_nodes=None, n_faces=None, n_edges=None, lazy_values=False):
-    """Wrapper for :meth:iris.tests.stock.mesh.sample_mesh`."""
+    """Sample mesh wrapper for :meth:iris.tests.stock.mesh.sample_mesh`."""
 
     def _external(*args, **kwargs):
         from iris.experimental.ugrid import save_mesh
@@ -112,7 +112,7 @@ def _external(*args, **kwargs):
 
 
 def sample_meshcoord(sample_mesh_kwargs=None, location="face", axis="x"):
-    """Wrapper for :meth:`iris.tests.stock.mesh.sample_meshcoord`.
+    """Sample meshcoord wrapper for :meth:`iris.tests.stock.mesh.sample_meshcoord`.
 
     Parameters deviate from the original as cannot pass a
     :class:`iris.experimental.ugrid.Mesh to the separate Python instance - must

benchmarks/benchmarks/sperf/combine_regions.py

@@ -83,7 +83,7 @@ def setup_cache(self):
             )
 
     def setup(self, n_cubesphere, imaginary_data=True, create_result_cube=True):
-        """The combine-tests "standard" setup operation.
+        """Combine-tests "standard" setup operation.
 
         Load the source cubes (full-mesh + region) from disk.
         These are specific to the cubesize parameter.

benchmarks/bm_runner.py

@@ -332,7 +332,7 @@ def add_asv_arguments(self) -> None:
     @staticmethod
     @abstractmethod
     def func(args: argparse.Namespace):
-        """The function to return when the subparser is parsed.
+        """Return when the subparser is parsed.
 
         `func` is then called, performing the user's selected sub-command.
 

docs/gallery_code/general/plot_custom_file_loading.py

@@ -90,7 +90,7 @@
 
 
 def load_NAME_III(filename):
-    """Loads the Met Office's NAME III grid output files.
+    """Load the Met Office's NAME III grid output files.
 
     Loads the Met Office's NAME III grid output files returning headers, column
     definitions and data arrays as 3 separate lists.
@@ -180,7 +180,7 @@ def load_NAME_III(filename):
 
 
 def NAME_to_cube(filenames, callback):
-    """Returns a generator of cubes given a list of filenames and a callback."""
+    """Return a generator of cubes given a list of filenames and a callback."""
     for filename in filenames:
         header, column_headings, data_arrays = load_NAME_III(filename)
 

docs/gallery_code/meteorology/plot_COP_maps.py

@@ -32,7 +32,7 @@
 
 
 def cop_metadata_callback(cube, field, filename):
-    """Function which adds an "Experiment" coordinate which comes from the filename."""
+    """Add an "Experiment" coordinate which comes from the filename."""
     # Extract the experiment name (such as A1B or E1) from the filename (in
     # this case it is just the start of the file name, before the first ".").
     fname = os.path.basename(filename)  # filename without path.

docs/gallery_tests/conftest.py

@@ -18,7 +18,7 @@
 
 @pytest.fixture
 def image_setup_teardown():
-    """Setup and teardown fixture.
+    """Perform setup and teardown fixture.
 
     Ensures all figures are closed before and after test to prevent one test
     polluting another if it fails with a figure unclosed.

docs/gallery_tests/test_gallery_examples.py

@@ -17,7 +17,7 @@
 
 
 def gallery_examples():
-    """Generator to yield all current gallery examples."""
+    """Entry point for generator to yield all current gallery examples."""
     for example_file in GALLERY_DIR.glob("*/plot*.py"):
         yield example_file.stem
 

lib/iris/_concatenate.py

@@ -151,7 +151,7 @@ def name(self):
 class _DerivedCoordAndDims(
     namedtuple("DerivedCoordAndDims", ["coord", "dims", "aux_factory"])
 ):
-    """Container for a derived coordinate and dimnesions(s).
+    """Container for a derived coordinate and dimensions(s).
 
     Container for a derived coordinate, the associated AuxCoordFactory, and the
     associated data dimension(s) spanned over a :class:`iris.cube.Cube`.
@@ -385,10 +385,7 @@ class _CubeSignature:
     """
 
     def __init__(self, cube):
-        """Represents the cube metadata and associated coordinate metadata.
-
-        Represents the cube metadata and associated coordinate metadata that
-        allows suitable cubes for concatenation to be identified.
+        """Represent the cube metadata and associated coordinate metadata.
 
         Parameters
         ----------
@@ -733,10 +730,7 @@ class _ProtoCube:
     """Framework for concatenating multiple source-cubes over one common dimension."""
 
     def __init__(self, cube):
-        """Create a new _ProtoCube and record the cube as a source-cube.
-
-        Create a new _ProtoCube from the given cube and record the cube
-        as a source-cube.
+        """Create a new _ProtoCube from the given cube and record the cube as a source-cube.
 
         Parameters
         ----------

lib/iris/_data_manager.py

@@ -117,7 +117,7 @@ def __ne__(self, other):
         return result
 
     def __repr__(self):
-        """Returns an string representation of the instance."""
+        """Return an string representation of the instance."""
         fmt = "{cls}({data!r})"
         result = fmt.format(data=self.core_data(), cls=type(self).__name__)
 
@@ -269,7 +269,7 @@ def shape(self):
         return self.core_data().shape
 
     def copy(self, data=None):
-        """Returns a deep copy of this :class:`~iris._data_manager.DataManager` instance.
+        """Return a deep copy of this :class:`~iris._data_manager.DataManager` instance.
 
         Parameters
         ----------

lib/iris/_merge.py

@@ -1182,7 +1182,7 @@ def _report_duplicate(self, nd_indexes, group_by_nd_index):
         raise iris.exceptions.DuplicateDataError(msg)
 
     def merge(self, unique=True):
-        """Returns the list of cubes resulting from merging the registered source-cubes.
+        """Return the list of cubes resulting from merging the registered source-cubes.
 
         Parameters
         ----------
@@ -1319,7 +1319,7 @@ def register(self, cube, error_on_mismatch=False):
         return match
 
     def _guess_axis(self, name):
-        """Returns a "best guess" axis name of the candidate dimension.
+        """Return a "best guess" axis name of the candidate dimension.
 
         Heuristic categoration of the candidate dimension
         (i.e. scalar_defn index) into either label 'T', 'Z', 'Y', 'X'
@@ -1564,7 +1564,7 @@ def _get_cube(self, data):
         return cube
 
     def _nd_index(self, position):
-        """Returns the n-dimensional index of thr source-cube, within the merged cube."""
+        """Return the n-dimensional index of thr source-cube, within the merged cube."""
         index = []
 
         # Determine the index of the source-cube cell for each dimension.

lib/iris/_representation/cube_printout.py

@@ -134,7 +134,7 @@ class CubePrinter:
     N_INDENT_EXTRA = 4
 
     def __init__(self, cube_or_summary):
-        """An object that provides a printout of a cube.
+        """Object that provides a printout of a cube.
 
         Parameters
         ----------

lib/iris/analysis/_interpolation.py

@@ -158,7 +158,7 @@ def get_xy_coords(cube, dim_coords=False):
 
 
 def snapshot_grid(cube):
-    """Helper function that returns deep copies of lateral (dimension) coordinates from a cube."""
+    """Return deep copies of lateral (dimension) coordinates from a cube."""
     x, y = get_xy_dim_coords(cube)
     return x.copy(), y.copy()
 

lib/iris/analysis/_regrid.py

@@ -407,7 +407,7 @@ def __init__(self, src_grid_cube, target_grid_cube, weights=None):
 
     @staticmethod
     def _get_horizontal_coord(cube, axis):
-        """Gets the horizontal coordinate on the supplied cube along the specified axis.
+        """Get the horizontal coordinate on the supplied cube along the specified axis.
 
         Parameters
         ----------

lib/iris/analysis/cartography.py

@@ -376,7 +376,7 @@ def _quadrant_area(radian_lat_bounds, radian_lon_bounds, radius_of_earth):
 
 
 def area_weights(cube, normalize=False):
-    r"""Returns an array of area weights, with the same dimensions as the cube.
+    r"""Return an array of area weights, with the same dimensions as the cube.
 
     This is a 2D lat/lon area weights array, repeated over the non lat/lon
     dimensions.

lib/iris/analysis/maths.py

@@ -323,7 +323,7 @@ def _add_subtract_common(
     dim=None,
     in_place=False,
 ):
-    """Function which shares common code between addition and subtraction of cubes.
+    """Share common code between addition and subtraction of cubes.
 
     Parameters
     ----------
@@ -532,7 +532,7 @@ def divide(cube, other, dim=None, in_place=False):
 
 
 def exponentiate(cube, exponent, in_place=False):
-    """Returns the result of the given cube to the power of a scalar.
+    """Return the result of the given cube to the power of a scalar.
 
     Parameters
     ----------
@@ -821,7 +821,7 @@ def _binary_op_common(
     in_place=False,
     sanitise_metadata=True,
 ):
-    """Function which shares common code between binary operations.
+    """Share common code between binary operations.
 
     Parameters
     ----------
@@ -1172,7 +1172,7 @@ def __call__(
         new_name=None,
         **kwargs_data_func,
     ):
-        """Applies the ifunc to the cube(s).
+        """Apply the ifunc to the cube(s).
 
         Parameters
         ----------

lib/iris/analysis/trajectory.py

@@ -37,7 +37,7 @@ class Trajectory:
     """A series of given waypoints with pre-calculated sample points."""
 
     def __init__(self, waypoints, sample_count=10):
-        """Defines a trajectory using a sequence of waypoints.
+        """Define a trajectory using a sequence of waypoints.
 
         Parameters
         ----------
@@ -128,7 +128,7 @@ def _get_interp_points(self):
         return [(k, v) for k, v in points.items()]
 
     def _src_cube_anon_dims(self, cube):
-        """A helper method to locate the index of anonymous dimensions.
+        """Locate the index of anonymous dimensions.
 
         A helper method to locate the index of anonymous dimensions on the
         interpolation target, ``cube``.
@@ -712,7 +712,7 @@ class UnstructuredNearestNeigbourRegridder:
     # TODO: cache the necessary bits of the operation so reuse can actually
     # be more efficient.
     def __init__(self, src_cube, target_grid_cube):
-        """A nearest-neighbour regridder.
+        """Nearest-neighbour regridder.
 
         A nearest-neighbour regridder to perform regridding from the source
         grid to the target grid.

lib/iris/common/_split_attribute_dicts.py

@@ -66,7 +66,9 @@ def _convert_pairedkeys_dict_to_splitattrs(dic):
 
 
 def adjust_for_split_attribute_dictionaries(operation):
-    """Decorator to make a function of attribute-dictionaries work with split attributes.
+    """Generate attribute-dictionaries to work with split attributes.
+
+    Decorator to make a function of attribute-dictionaries work with split attributes.
 
     The wrapped function of attribute-dictionaries is currently always one of "equals",
     "combine" or "difference", with signatures like :
@@ -91,6 +93,7 @@ def adjust_for_split_attribute_dictionaries(operation):
     "Split" dictionaries  are all of class :class:`~iris.cube.CubeAttrsDict`, since
     the only usage of 'split' attribute dictionaries is in Cubes (i.e. they are not
     used for cube components).
+
     """
 
     @wraps(operation)