Apply assorted ruff/Pylint rules (PL) / Enforce PLE rules (#10366)

* Apply ruff/Pylint rule PLC0206

PLC0206 Extracting value from dictionary without calling `.items()`

* Apply ruff/Pylint rule PLR1714

PLR1714 Consider merging multiple comparison

* Apply ruff/Pylint rule PLR2044

PLR2044 Line with empty comment

* Apply ruff/Pylint rule PLR5501

PLR5501 Use `elif` instead of `else` then `if`, to reduce indentation

* Apply ruff/Pylint rule PLW0127

PLW0127 Self-assignment of variable

The intent of the "flake8 workaround" might have been to avoid F811 errors.
These F811 errors exist only because of the ignored F401 errors. So ignore
F401 errors more precisely to clarify the situation.

* Enforce ruff/Pylint Error rules (PLE)

Author: DimitriPapadopoulos

pyproject.toml

@@ -258,6 +258,7 @@ extend-select = [
   "PERF", # Perflint
   "W",    # pycodestyle warnings
   "PGH",  # pygrep-hooks
+  "PLE",  # Pylint Errors
   "UP",   # pyupgrade
   "FURB", # refurb
   "RUF",

xarray/backends/common.py

@@ -338,11 +338,10 @@ def add(self, source, target, region=None):
             self.sources.append(source)
             self.targets.append(target)
             self.regions.append(region)
+        elif region:
+            target[region] = source
         else:
-            if region:
-                target[region] = source
-            else:
-                target[...] = source
+            target[...] = source
 
     def sync(self, compute=True, chunkmanager_store_kwargs=None):
         if self.sources:

xarray/coding/cftime_offsets.py

@@ -279,9 +279,8 @@ def _adjust_n_years(other, n, month, reference_day):
     if n > 0:
         if other.month < month or (other.month == month and other.day < reference_day):
             n -= 1
-    else:
-        if other.month > month or (other.month == month and other.day > reference_day):
-            n += 1
+    elif other.month > month or (other.month == month and other.day > reference_day):
+        n += 1
     return n
 
 
@@ -353,12 +352,11 @@ def roll_qtrday(
             # pretend to roll back if on same month but
             # before compare_day
             n -= 1
-    else:
-        if months_since > 0 or (
-            months_since == 0 and other.day > _get_day_of_month(other, day_option)
-        ):
-            # make sure to roll forward, so negate
-            n += 1
+    elif months_since > 0 or (
+        months_since == 0 and other.day > _get_day_of_month(other, day_option)
+    ):
+        # make sure to roll forward, so negate
+        n += 1
     return n
 
 
@@ -815,13 +813,12 @@ def delta_to_tick(delta: timedelta | pd.Timedelta) -> Tick:
                 return Minute(n=seconds // 60)
             else:
                 return Second(n=seconds)
+    # Regardless of the days and seconds this will always be a Millisecond
+    # or Microsecond object
+    elif delta.microseconds % 1_000 == 0:
+        return Millisecond(n=delta.microseconds // 1_000)
     else:
-        # Regardless of the days and seconds this will always be a Millisecond
-        # or Microsecond object
-        if delta.microseconds % 1_000 == 0:
-            return Millisecond(n=delta.microseconds // 1_000)
-        else:
-            return Microsecond(n=delta.microseconds)
+        return Microsecond(n=delta.microseconds)
 
 
 def to_cftime_datetime(date_str_or_date, calendar=None):
@@ -1615,11 +1612,10 @@ def date_range_like(source, calendar, use_cftime=None):
         source_calendar = "standard"
         source_start = default_precision_timestamp(source_start)
         source_end = default_precision_timestamp(source_end)
-    else:
-        if isinstance(source, CFTimeIndex):
-            source_calendar = source.calendar
-        else:  # DataArray
-            source_calendar = source.dt.calendar
+    elif isinstance(source, CFTimeIndex):
+        source_calendar = source.calendar
+    else:  # DataArray
+        source_calendar = source.dt.calendar
 
     if calendar == source_calendar and is_np_datetime_like(source.dtype) ^ use_cftime:
         return source

xarray/coding/times.py

@@ -579,9 +579,8 @@ def decode_cf_datetime(
                     "'time_unit' or specify 'use_cftime=True'.",
                     SerializationWarning,
                 )
-            else:
-                if _is_standard_calendar(calendar):
-                    dates = cftime_to_nptime(dates, time_unit=time_unit)
+            elif _is_standard_calendar(calendar):
+                dates = cftime_to_nptime(dates, time_unit=time_unit)
     elif use_cftime:
         dates = _decode_datetime_with_cftime(flat_num_dates, units, calendar)
     else:

xarray/computation/apply_ufunc.py

@@ -445,17 +445,16 @@ def apply_dict_of_variables_vfunc(
         core_dim_present = _check_core_dims(signature, variable_args, name)
         if core_dim_present is True:
             result_vars[name] = func(*variable_args)
+        elif on_missing_core_dim == "raise":
+            raise ValueError(core_dim_present)
+        elif on_missing_core_dim == "copy":
+            result_vars[name] = variable_args[0]
+        elif on_missing_core_dim == "drop":
+            pass
         else:
-            if on_missing_core_dim == "raise":
-                raise ValueError(core_dim_present)
-            elif on_missing_core_dim == "copy":
-                result_vars[name] = variable_args[0]
-            elif on_missing_core_dim == "drop":
-                pass
-            else:
-                raise ValueError(
-                    f"Invalid value for `on_missing_core_dim`: {on_missing_core_dim!r}"
-                )
+            raise ValueError(
+                f"Invalid value for `on_missing_core_dim`: {on_missing_core_dim!r}"
+            )
 
     if signature.num_outputs > 1:
         return _unpack_dict_tuples(result_vars, signature.num_outputs)
@@ -809,11 +808,10 @@ def func(*arrays):
             raise ValueError(
                 f"unknown setting for chunked array handling in apply_ufunc: {dask}"
             )
-    else:
-        if vectorize:
-            func = _vectorize(
-                func, signature, output_dtypes=output_dtypes, exclude_dims=exclude_dims
-            )
+    elif vectorize:
+        func = _vectorize(
+            func, signature, output_dtypes=output_dtypes, exclude_dims=exclude_dims
+        )
 
     result_data = func(*input_data)
 

xarray/computation/rolling.py

@@ -1253,18 +1253,17 @@ def wrapped_func(
             for c, v in self.obj.coords.items():
                 if c == self.obj.name:
                     coords[c] = reduced
+                elif any(d in self.windows for d in v.dims):
+                    coords[c] = v.variable.coarsen(
+                        self.windows,
+                        self.coord_func[c],
+                        self.boundary,
+                        self.side,
+                        keep_attrs,
+                        **kwargs,
+                    )
                 else:
-                    if any(d in self.windows for d in v.dims):
-                        coords[c] = v.variable.coarsen(
-                            self.windows,
-                            self.coord_func[c],
-                            self.boundary,
-                            self.side,
-                            keep_attrs,
-                            **kwargs,
-                        )
-                    else:
-                        coords[c] = v
+                    coords[c] = v
             return DataArray(
                 reduced, dims=self.obj.dims, coords=coords, name=self.obj.name
             )

xarray/conventions.py

@@ -226,17 +226,16 @@ def decode_cf_variable(
                     DeprecationWarning,
                 )
             decode_times = CFDatetimeCoder(use_cftime=use_cftime)
-        else:
-            if use_cftime is not None:
-                raise TypeError(
-                    "Usage of 'use_cftime' as a kwarg is not allowed "
-                    "if a 'CFDatetimeCoder' instance is passed to "
-                    "'decode_times'. Please set 'use_cftime' "
-                    "when initializing 'CFDatetimeCoder' instead.\n"
-                    "Example usage:\n"
-                    "    time_coder = xr.coders.CFDatetimeCoder(use_cftime=True)\n"
-                    "    ds = xr.open_dataset(decode_times=time_coder)\n",
-                )
+        elif use_cftime is not None:
+            raise TypeError(
+                "Usage of 'use_cftime' as a kwarg is not allowed "
+                "if a 'CFDatetimeCoder' instance is passed to "
+                "'decode_times'. Please set 'use_cftime' "
+                "when initializing 'CFDatetimeCoder' instead.\n"
+                "Example usage:\n"
+                "    time_coder = xr.coders.CFDatetimeCoder(use_cftime=True)\n"
+                "    ds = xr.open_dataset(decode_times=time_coder)\n",
+            )
         var = decode_times.decode(var, name=name)
 
     if decode_endianness and not var.dtype.isnative:

xarray/core/dataset.py

@@ -2904,9 +2904,8 @@ def sel(
             for k, v in query_results.variables.items():
                 if v.dims:
                     no_scalar_variables[k] = v
-                else:
-                    if k in self._coord_names:
-                        query_results.drop_coords.append(k)
+                elif k in self._coord_names:
+                    query_results.drop_coords.append(k)
             query_results.variables = no_scalar_variables
 
         result = self.isel(indexers=query_results.dim_indexers, drop=drop)
@@ -4552,26 +4551,25 @@ def expand_dims(
                     for d, c in zip_axis_dim:
                         all_dims.insert(d, c)
                     variables[k] = v.set_dims(dict(all_dims))
-            else:
-                if k not in variables:
-                    if k in coord_names and create_index_for_new_dim:
-                        # If dims includes a label of a non-dimension coordinate,
-                        # it will be promoted to a 1D coordinate with a single value.
-                        index, index_vars = create_default_index_implicit(v.set_dims(k))
-                        indexes[k] = index
-                        variables.update(index_vars)
-                    else:
-                        if create_index_for_new_dim:
-                            warnings.warn(
-                                f"No index created for dimension {k} because variable {k} is not a coordinate. "
-                                f"To create an index for {k}, please first call `.set_coords('{k}')` on this object.",
-                                UserWarning,
-                                stacklevel=2,
-                            )
+            elif k not in variables:
+                if k in coord_names and create_index_for_new_dim:
+                    # If dims includes a label of a non-dimension coordinate,
+                    # it will be promoted to a 1D coordinate with a single value.
+                    index, index_vars = create_default_index_implicit(v.set_dims(k))
+                    indexes[k] = index
+                    variables.update(index_vars)
+                else:
+                    if create_index_for_new_dim:
+                        warnings.warn(
+                            f"No index created for dimension {k} because variable {k} is not a coordinate. "
+                            f"To create an index for {k}, please first call `.set_coords('{k}')` on this object.",
+                            UserWarning,
+                            stacklevel=2,
+                        )
 
-                        # create 1D variable without creating a new index
-                        new_1d_var = v.set_dims(k)
-                        variables.update({k: new_1d_var})
+                    # create 1D variable without creating a new index
+                    new_1d_var = v.set_dims(k)
+                    variables.update({k: new_1d_var})
 
         return self._replace_with_new_dims(
             variables, coord_names=coord_names, indexes=indexes
@@ -4890,9 +4888,8 @@ def set_xindex(
                 index_cls = PandasIndex
             else:
                 index_cls = PandasMultiIndex
-        else:
-            if not issubclass(index_cls, Index):
-                raise TypeError(f"{index_cls} is not a subclass of xarray.Index")
+        elif not issubclass(index_cls, Index):
+            raise TypeError(f"{index_cls} is not a subclass of xarray.Index")
 
         invalid_coords = set(coord_names) - self._coord_names
 
@@ -6744,34 +6741,33 @@ def reduce(
             if name in self.coords:
                 if not reduce_dims:
                     variables[name] = var
-            else:
-                if (
-                    # Some reduction functions (e.g. std, var) need to run on variables
-                    # that don't have the reduce dims: PR5393
-                    not is_extension_array_dtype(var.dtype)
-                    and (
-                        not reduce_dims
-                        or not numeric_only
-                        or np.issubdtype(var.dtype, np.number)
-                        or (var.dtype == np.bool_)
-                    )
-                ):
-                    # prefer to aggregate over axis=None rather than
-                    # axis=(0, 1) if they will be equivalent, because
-                    # the former is often more efficient
-                    # keep single-element dims as list, to support Hashables
-                    reduce_maybe_single = (
-                        None
-                        if len(reduce_dims) == var.ndim and var.ndim != 1
-                        else reduce_dims
-                    )
-                    variables[name] = var.reduce(
-                        func,
-                        dim=reduce_maybe_single,
-                        keep_attrs=keep_attrs,
-                        keepdims=keepdims,
-                        **kwargs,
-                    )
+            elif (
+                # Some reduction functions (e.g. std, var) need to run on variables
+                # that don't have the reduce dims: PR5393
+                not is_extension_array_dtype(var.dtype)
+                and (
+                    not reduce_dims
+                    or not numeric_only
+                    or np.issubdtype(var.dtype, np.number)
+                    or (var.dtype == np.bool_)
+                )
+            ):
+                # prefer to aggregate over axis=None rather than
+                # axis=(0, 1) if they will be equivalent, because
+                # the former is often more efficient
+                # keep single-element dims as list, to support Hashables
+                reduce_maybe_single = (
+                    None
+                    if len(reduce_dims) == var.ndim and var.ndim != 1
+                    else reduce_dims
+                )
+                variables[name] = var.reduce(
+                    func,
+                    dim=reduce_maybe_single,
+                    keep_attrs=keep_attrs,
+                    keepdims=keepdims,
+                    **kwargs,
+                )
 
         coord_names = {k for k in self.coords if k in variables}
         indexes = {k: v for k, v in self._indexes.items() if k in variables}
@@ -7970,8 +7966,6 @@ def sortby(
             variables = variables(self)
         if not isinstance(variables, list):
             variables = [variables]
-        else:
-            variables = variables
         arrays = [v if isinstance(v, DataArray) else self[v] for v in variables]
         aligned_vars = align(self, *arrays, join="left")
         aligned_self = cast("Self", aligned_vars[0])
@@ -8395,25 +8389,24 @@ def _integrate_one(self, coord, datetime_unit=None, cumulative=False):
                 if dim not in v.dims or cumulative:
                     variables[k] = v
                     coord_names.add(k)
-            else:
-                if k in self.data_vars and dim in v.dims:
-                    coord_data = to_like_array(coord_var.data, like=v.data)
-                    if _contains_datetime_like_objects(v):
-                        v = datetime_to_numeric(v, datetime_unit=datetime_unit)
-                    if cumulative:
-                        integ = duck_array_ops.cumulative_trapezoid(
-                            v.data, coord_data, axis=v.get_axis_num(dim)
-                        )
-                        v_dims = v.dims
-                    else:
-                        integ = duck_array_ops.trapz(
-                            v.data, coord_data, axis=v.get_axis_num(dim)
-                        )
-                        v_dims = list(v.dims)
-                        v_dims.remove(dim)
-                    variables[k] = Variable(v_dims, integ)
+            elif k in self.data_vars and dim in v.dims:
+                coord_data = to_like_array(coord_var.data, like=v.data)
+                if _contains_datetime_like_objects(v):
+                    v = datetime_to_numeric(v, datetime_unit=datetime_unit)
+                if cumulative:
+                    integ = duck_array_ops.cumulative_trapezoid(
+                        v.data, coord_data, axis=v.get_axis_num(dim)
+                    )
+                    v_dims = v.dims
                 else:
-                    variables[k] = v
+                    integ = duck_array_ops.trapz(
+                        v.data, coord_data, axis=v.get_axis_num(dim)
+                    )
+                    v_dims = list(v.dims)
+                    v_dims.remove(dim)
+                variables[k] = Variable(v_dims, integ)
+            else:
+                variables[k] = v
         indexes = {k: v for k, v in self._indexes.items() if k in variables}
         return self._replace_with_new_dims(
             variables, coord_names=coord_names, indexes=indexes