Fix mypy errors in xarray.py, xrutils.py, cache.py (#144)

* update dim typing

* Fix mypy errors in xarray.py

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* start mypy ci

* Use T_DataArray and T_Dataset

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* Add mypy ignores

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* correct typing a bit

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* test newer flake8 if ellipsis passes there

* Allow ellipsis in flake8

* Update core.py

* Update xarray.py

* Update setup.cfg

* Update xarray.py

* Update xarray.py

* Update xarray.py

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* Update xarray.py

* Update pyproject.toml

* Update xarray.py

* Update xarray.py

* hopefully no more pytest errors.

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* make sure expected_groups doesn't have None

* Update flox/xarray.py

Co-authored-by: Deepak Cherian <[email protected]>

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* ds_broad and longer comment

* Use same for loop for similar things.

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* fix xrutils.py

* fix errors in cache.py

* Turn off mypy check

* Update flox/xarray.py

Co-authored-by: Deepak Cherian <[email protected]>

* Update flox/xarray.py

Co-authored-by: Deepak Cherian <[email protected]>

* Use if else format to avoid tuple creation

* Update xarray.py

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Deepak Cherian <[email protected]>

flox/cache.py

@@ -8,4 +8,4 @@
     cache = cachey.Cache(1e6)
     memoize = partial(cache.memoize, key=dask.base.tokenize)
 except ImportError:
-    memoize = lambda x: x
+    memoize = lambda x: x  # type: ignore

flox/core.py

@@ -5,7 +5,16 @@
 import operator
 from collections import namedtuple
 from functools import partial, reduce
-from typing import TYPE_CHECKING, Any, Callable, Dict, Mapping, Sequence, Union
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Dict,
+    Iterable,
+    Mapping,
+    Sequence,
+    Union,
+)
 
 import numpy as np
 import numpy_groupies as npg
@@ -1282,8 +1291,8 @@ def _assert_by_is_aligned(shape, by):
 
 
 def _convert_expected_groups_to_index(
-    expected_groups: tuple, isbin: bool, sort: bool
-) -> pd.Index | None:
+    expected_groups: Iterable, isbin: Sequence[bool], sort: bool
+) -> tuple[pd.Index | None]:
     out = []
     for ex, isbin_ in zip(expected_groups, isbin):
         if isinstance(ex, pd.IntervalIndex) or (isinstance(ex, pd.Index) and not isbin):

flox/xarray.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Hashable, Iterable, Sequence
+from typing import TYPE_CHECKING, Any, Hashable, Iterable, Sequence, Union
 
 import numpy as np
 import pandas as pd
@@ -19,7 +19,10 @@
 from .xrutils import _contains_cftime_datetimes, _to_pytimedelta, datetime_to_numeric
 
 if TYPE_CHECKING:
-    from xarray import DataArray, Dataset, Resample
+    from xarray.core.resample import Resample
+    from xarray.core.types import T_DataArray, T_Dataset
+
+    Dims = Union[str, Iterable[Hashable], None]
 
 
 def _get_input_core_dims(group_names, dim, ds, grouper_dims):
@@ -51,13 +54,13 @@ def lookup_order(dimension):
 
 
 def xarray_reduce(
-    obj: Dataset | DataArray,
-    *by: DataArray | Iterable[str] | Iterable[DataArray],
+    obj: T_Dataset | T_DataArray,
+    *by: T_DataArray | Hashable,
     func: str | Aggregation,
     expected_groups=None,
     isbin: bool | Sequence[bool] = False,
     sort: bool = True,
-    dim: Hashable = None,
+    dim: Dims | ellipsis = None,
     split_out: int = 1,
     fill_value=None,
     method: str = "map-reduce",
@@ -203,8 +206,11 @@ def xarray_reduce(
     if keep_attrs is None:
         keep_attrs = True
 
-    if isinstance(isbin, bool):
-        isbin = (isbin,) * nby
+    if isinstance(isbin, Sequence):
+        isbins = isbin
+    else:
+        isbins = (isbin,) * nby
+
     if expected_groups is None:
         expected_groups = (None,) * nby
     if isinstance(expected_groups, (np.ndarray, list)):  # TODO: test for list
@@ -217,78 +223,86 @@ def xarray_reduce(
         raise NotImplementedError
 
     # eventually drop the variables we are grouping by
-    maybe_drop = [b for b in by if isinstance(b, str)]
+    maybe_drop = [b for b in by if isinstance(b, Hashable)]
     unindexed_dims = tuple(
         b
-        for b, isbin_ in zip(by, isbin)
-        if isinstance(b, str) and not isbin_ and b in obj.dims and b not in obj.indexes
+        for b, isbin_ in zip(by, isbins)
+        if isinstance(b, Hashable) and not isbin_ and b in obj.dims and b not in obj.indexes
     )
 
-    by: tuple[DataArray] = tuple(obj[g] if isinstance(g, str) else g for g in by)  # type: ignore
+    by_da = tuple(obj[g] if isinstance(g, Hashable) else g for g in by)
 
     grouper_dims = []
-    for g in by:
+    for g in by_da:
         for d in g.dims:
             if d not in grouper_dims:
                 grouper_dims.append(d)
 
-    if isinstance(obj, xr.DataArray):
-        ds = obj._to_temp_dataset()
-    else:
+    if isinstance(obj, xr.Dataset):
         ds = obj
+    else:
+        ds = obj._to_temp_dataset()
 
     ds = ds.drop_vars([var for var in maybe_drop if var in ds.variables])
 
     if dim is Ellipsis:
         if nby > 1:
             raise NotImplementedError("Multiple by are not allowed when dim is Ellipsis.")
-        dim = tuple(obj.dims)
-        if by[0].name in ds.dims and not isbin[0]:
-            dim = tuple(d for d in dim if d != by[0].name)
+        name_ = by_da[0].name
+        if name_ in ds.dims and not isbins[0]:
+            dim_tuple = tuple(d for d in obj.dims if d != name_)
+        else:
+            dim_tuple = tuple(obj.dims)
     elif dim is not None:
-        dim = _atleast_1d(dim)
+        dim_tuple = _atleast_1d(dim)
     else:
-        dim = tuple()
+        dim_tuple = tuple()
 
     # broadcast all variables against each other along all dimensions in `by` variables
     # don't exclude `dim` because it need not be a dimension in any of the `by` variables!
     # in the case where dim is Ellipsis, and by.ndim < obj.ndim
     # then we also broadcast `by` to all `obj.dims`
     # TODO: avoid this broadcasting
-    exclude_dims = tuple(d for d in ds.dims if d not in grouper_dims and d not in dim)
-    ds, *by = xr.broadcast(ds, *by, exclude=exclude_dims)
+    exclude_dims = tuple(d for d in ds.dims if d not in grouper_dims and d not in dim_tuple)
+    ds_broad, *by_broad = xr.broadcast(ds, *by_da, exclude=exclude_dims)
 
-    if not dim:
-        dim = tuple(by[0].dims)
+    # all members of by_broad have the same dimensions
+    # so we just pull by_broad[0].dims if dim is None
+    if not dim_tuple:
+        dim_tuple = tuple(by_broad[0].dims)
 
-    if any(d not in grouper_dims and d not in obj.dims for d in dim):
+    if any(d not in grouper_dims and d not in obj.dims for d in dim_tuple):
         raise ValueError(f"Cannot reduce over absent dimensions {dim}.")
 
-    dims_not_in_groupers = tuple(d for d in dim if d not in grouper_dims)
-    if dims_not_in_groupers == tuple(dim) and not any(isbin):
+    dims_not_in_groupers = tuple(d for d in dim_tuple if d not in grouper_dims)
+    if dims_not_in_groupers == tuple(dim_tuple) and not any(isbins):
         # reducing along a dimension along which groups do not vary
         # This is really just a normal reduction.
         # This is not right when binning so we exclude.
-        if skipna and isinstance(func, str):
-            dsfunc = func[3:]
+        if isinstance(func, str):
+            dsfunc = func[3:] if skipna else func
         else:
-            dsfunc = func
+            raise NotImplementedError(
+                "func must be a string when reducing along a dimension not present in `by`"
+            )
         # TODO: skipna needs test
-        result = getattr(ds, dsfunc)(dim=dim, skipna=skipna)
+        result = getattr(ds_broad, dsfunc)(dim=dim_tuple, skipna=skipna)
         if isinstance(obj, xr.DataArray):
             return obj._from_temp_dataset(result)
         else:
             return result
 
-    axis = tuple(range(-len(dim), 0))
-    group_names = tuple(g.name if not binned else f"{g.name}_bins" for g, binned in zip(by, isbin))
-
-    group_shape = [None] * len(by)
-    expected_groups = list(expected_groups)
+    axis = tuple(range(-len(dim_tuple), 0))
 
     # Set expected_groups and convert to index since we need coords, sizes
     # for output xarray objects
-    for idx, (b, expect, isbin_) in enumerate(zip(by, expected_groups, isbin)):
+    expected_groups = list(expected_groups)
+    group_names: tuple[Any, ...] = ()
+    group_sizes: dict[Any, int] = {}
+    for idx, (b_, expect, isbin_) in enumerate(zip(by_broad, expected_groups, isbins)):
+        group_name = b_.name if not isbin_ else f"{b_.name}_bins"
+        group_names += (group_name,)
+
         if isbin_ and isinstance(expect, int):
             raise NotImplementedError(
                 "flox does not support binning into an integer number of bins yet."
@@ -297,13 +311,21 @@ def xarray_reduce(
             if isbin_:
                 raise ValueError(
                     f"Please provided bin edges for group variable {idx} "
-                    f"named {group_names[idx]} in expected_groups."
+                    f"named {group_name} in expected_groups."
                 )
-            expected_groups[idx] = _get_expected_groups(b.data, sort=sort, raise_if_dask=True)
-
-    expected_groups = _convert_expected_groups_to_index(expected_groups, isbin, sort=sort)
-    group_shape = tuple(len(e) for e in expected_groups)
-    group_sizes = dict(zip(group_names, group_shape))
+            expect_ = _get_expected_groups(b_.data, sort=sort, raise_if_dask=True)
+        else:
+            expect_ = expect
+        expect_index = _convert_expected_groups_to_index((expect_,), (isbin_,), sort=sort)[0]
+
+        # The if-check is for type hinting mainly, it narrows down the return
+        # type of _convert_expected_groups_to_index to pure pd.Index:
+        if expect_index is not None:
+            expected_groups[idx] = expect_index
+            group_sizes[group_name] = len(expect_index)
+        else:
+            # This will never be reached
+            raise ValueError("expect_index cannot be None")
 
     def wrapper(array, *by, func, skipna, **kwargs):
         # Handle skipna here because I need to know dtype to make a good default choice.
@@ -349,20 +371,20 @@ def wrapper(array, *by, func, skipna, **kwargs):
     if isinstance(obj, xr.Dataset):
         # broadcasting means the group dim gets added to ds, so we check the original obj
         for k, v in obj.data_vars.items():
-            is_missing_dim = not (any(d in v.dims for d in dim))
+            is_missing_dim = not (any(d in v.dims for d in dim_tuple))
             if is_missing_dim:
                 missing_dim[k] = v
 
-    input_core_dims = _get_input_core_dims(group_names, dim, ds, grouper_dims)
+    input_core_dims = _get_input_core_dims(group_names, dim_tuple, ds_broad, grouper_dims)
     input_core_dims += [input_core_dims[-1]] * (nby - 1)
 
     actual = xr.apply_ufunc(
         wrapper,
-        ds.drop_vars(tuple(missing_dim)).transpose(..., *grouper_dims),
-        *by,
+        ds_broad.drop_vars(tuple(missing_dim)).transpose(..., *grouper_dims),
+        *by_broad,
         input_core_dims=input_core_dims,
         # for xarray's test_groupby_duplicate_coordinate_labels
-        exclude_dims=set(dim),
+        exclude_dims=set(dim_tuple),
         output_core_dims=[group_names],
         dask="allowed",
         dask_gufunc_kwargs=dict(output_sizes=group_sizes),
@@ -379,27 +401,27 @@ def wrapper(array, *by, func, skipna, **kwargs):
             "engine": engine,
             "reindex": reindex,
             "expected_groups": tuple(expected_groups),
-            "isbin": isbin,
+            "isbin": isbins,
             "finalize_kwargs": finalize_kwargs,
         },
     )
 
     # restore non-dim coord variables without the core dimension
     # TODO: shouldn't apply_ufunc handle this?
-    for var in set(ds.variables) - set(ds.dims):
-        if all(d not in ds[var].dims for d in dim):
-            actual[var] = ds[var]
+    for var in set(ds_broad.variables) - set(ds_broad.dims):
+        if all(d not in ds_broad[var].dims for d in dim_tuple):
+            actual[var] = ds_broad[var]
 
-    for name, expect, by_ in zip(group_names, expected_groups, by):
+    for name, expect, by_ in zip(group_names, expected_groups, by_broad):
         # Can't remove this till xarray handles IntervalIndex
         if isinstance(expect, pd.IntervalIndex):
             expect = expect.to_numpy()
         if isinstance(actual, xr.Dataset) and name in actual:
             actual = actual.drop_vars(name)
         # When grouping by MultiIndex, expect is an pd.Index wrapping
         # an object array of tuples
-        if name in ds.indexes and isinstance(ds.indexes[name], pd.MultiIndex):
-            levelnames = ds.indexes[name].names
+        if name in ds_broad.indexes and isinstance(ds_broad.indexes[name], pd.MultiIndex):
+            levelnames = ds_broad.indexes[name].names
             expect = pd.MultiIndex.from_tuples(expect.values, names=levelnames)
             actual[name] = expect
             if Version(xr.__version__) > Version("2022.03.0"):
@@ -414,18 +436,17 @@ def wrapper(array, *by, func, skipna, **kwargs):
 
     if nby == 1:
         for var in actual:
-            if isinstance(obj, xr.DataArray):
-                template = obj
-            else:
+            if isinstance(obj, xr.Dataset):
                 template = obj[var]
+            else:
+                template = obj
+
             if actual[var].ndim > 1:
-                actual[var] = _restore_dim_order(actual[var], template, by[0])
+                actual[var] = _restore_dim_order(actual[var], template, by_broad[0])
 
     if missing_dim:
         for k, v in missing_dim.items():
-            missing_group_dims = {
-                dim: size for dim, size in group_sizes.items() if dim not in v.dims
-            }
+            missing_group_dims = {d: size for d, size in group_sizes.items() if d not in v.dims}
             # The expand_dims is for backward compat with xarray's questionable behaviour
             if missing_group_dims:
                 actual[k] = v.expand_dims(missing_group_dims).variable
@@ -439,9 +460,9 @@ def wrapper(array, *by, func, skipna, **kwargs):
 
 
 def rechunk_for_cohorts(
-    obj: DataArray | Dataset,
+    obj: T_DataArray | T_Dataset,
     dim: str,
-    labels: DataArray,
+    labels: T_DataArray,
     force_new_chunk_at,
     chunksize: int | None = None,
     ignore_old_chunks: bool = False,
@@ -486,7 +507,7 @@ def rechunk_for_cohorts(
     )
 
 
-def rechunk_for_blockwise(obj: DataArray | Dataset, dim: str, labels: DataArray):
+def rechunk_for_blockwise(obj: T_DataArray | T_Dataset, dim: str, labels: T_DataArray):
     """
     Rechunks array so that group boundaries line up with chunk boundaries, allowing
     embarassingly parallel group reductions.

flox/xrutils.py

@@ -19,7 +19,7 @@
 
     dask_array_type = dask.array.Array
 except ImportError:
-    dask_array_type = ()
+    dask_array_type = ()  # type: ignore
 
 
 def asarray(data, xp=np):

setup.cfg

@@ -57,3 +57,5 @@ per-file-ignores =
 exclude=
     .eggs
     doc
+builtins =
+    ellipsis