Refactor dataset groupby tests (#5506)

dcherian · mathause · web-flow · commit 1f5c63379e1a · 2021-06-22T10:00:15.000-06:00
Co-authored-by: Mathias Hauser &lt;mathause@users.noreply.github.com&gt;
diff --git a/xarray/tests/__init__.py b/xarray/tests/__init__.py
@@ -6,11 +6,13 @@
 from unittest import mock  # noqa: F401
 
 import numpy as np
+import pandas as pd
 import pytest
 from numpy.testing import assert_array_equal  # noqa: F401
 from pandas.testing import assert_frame_equal  # noqa: F401
 
 import xarray.testing
+from xarray import Dataset
 from xarray.core import utils
 from xarray.core.duck_array_ops import allclose_or_equiv  # noqa: F401
 from xarray.core.indexing import ExplicitlyIndexed
@@ -200,3 +202,30 @@ def assert_allclose(a, b, **kwargs):
     xarray.testing.assert_allclose(a, b, **kwargs)
     xarray.testing._assert_internal_invariants(a)
     xarray.testing._assert_internal_invariants(b)
+
+
+def create_test_data(seed=None, add_attrs=True):
+    rs = np.random.RandomState(seed)
+    _vars = {
+        "var1": ["dim1", "dim2"],
+        "var2": ["dim1", "dim2"],
+        "var3": ["dim3", "dim1"],
+    }
+    _dims = {"dim1": 8, "dim2": 9, "dim3": 10}
+
+    obj = Dataset()
+    obj["dim2"] = ("dim2", 0.5 * np.arange(_dims["dim2"]))
+    obj["dim3"] = ("dim3", list("abcdefghij"))
+    obj["time"] = ("time", pd.date_range("2000-01-01", periods=20))
+    for v, dims in sorted(_vars.items()):
+        data = rs.normal(size=tuple(_dims[d] for d in dims))
+        obj[v] = (dims, data)
+        if add_attrs:
+            obj[v].attrs = {"foo": "variable"}
+    obj.coords["numbers"] = (
+        "dim3",
+        np.array([0, 1, 2, 0, 0, 1, 1, 2, 2, 3], dtype="int64"),
+    )
+    obj.encoding = {"foo": "bar"}
+    assert all(obj.data.flags.writeable for obj in obj.variables.values())
+    return obj
diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
@@ -39,6 +39,7 @@
     assert_array_equal,
     assert_equal,
     assert_identical,
+    create_test_data,
     has_cftime,
     has_dask,
     requires_bottleneck,
@@ -62,33 +63,6 @@
 ]
 
 
-def create_test_data(seed=None, add_attrs=True):
-    rs = np.random.RandomState(seed)
-    _vars = {
-        "var1": ["dim1", "dim2"],
-        "var2": ["dim1", "dim2"],
-        "var3": ["dim3", "dim1"],
-    }
-    _dims = {"dim1": 8, "dim2": 9, "dim3": 10}
-
-    obj = Dataset()
-    obj["dim2"] = ("dim2", 0.5 * np.arange(_dims["dim2"]))
-    obj["dim3"] = ("dim3", list("abcdefghij"))
-    obj["time"] = ("time", pd.date_range("2000-01-01", periods=20))
-    for v, dims in sorted(_vars.items()):
-        data = rs.normal(size=tuple(_dims[d] for d in dims))
-        obj[v] = (dims, data)
-        if add_attrs:
-            obj[v].attrs = {"foo": "variable"}
-    obj.coords["numbers"] = (
-        "dim3",
-        np.array([0, 1, 2, 0, 0, 1, 1, 2, 2, 3], dtype="int64"),
-    )
-    obj.encoding = {"foo": "bar"}
-    assert all(obj.data.flags.writeable for obj in obj.variables.values())
-    return obj
-
-
 def create_append_test_data(seed=None):
     rs = np.random.RandomState(seed)
 
@@ -3785,173 +3759,6 @@ def test_squeeze_drop(self):
         selected = data.squeeze(drop=True)
         assert_identical(data, selected)
 
-    def test_groupby(self):
-        data = Dataset(
-            {"z": (["x", "y"], np.random.randn(3, 5))},
-            {"x": ("x", list("abc")), "c": ("x", [0, 1, 0]), "y": range(5)},
-        )
-        groupby = data.groupby("x")
-        assert len(groupby) == 3
-        expected_groups = {"a": 0, "b": 1, "c": 2}
-        assert groupby.groups == expected_groups
-        expected_items = [
-            ("a", data.isel(x=0)),
-            ("b", data.isel(x=1)),
-            ("c", data.isel(x=2)),
-        ]
-        for actual, expected in zip(groupby, expected_items):
-            assert actual[0] == expected[0]
-            assert_equal(actual[1], expected[1])
-
-        def identity(x):
-            return x
-
-        for k in ["x", "c", "y"]:
-            actual = data.groupby(k, squeeze=False).map(identity)
-            assert_equal(data, actual)
-
-    def test_groupby_returns_new_type(self):
-        data = Dataset({"z": (["x", "y"], np.random.randn(3, 5))})
-
-        actual = data.groupby("x").map(lambda ds: ds["z"])
-        expected = data["z"]
-        assert_identical(expected, actual)
-
-        actual = data["z"].groupby("x").map(lambda x: x.to_dataset())
-        expected = data
-        assert_identical(expected, actual)
-
-    def test_groupby_iter(self):
-        data = create_test_data()
-        for n, (t, sub) in enumerate(list(data.groupby("dim1"))[:3]):
-            assert data["dim1"][n] == t
-            assert_equal(data["var1"][n], sub["var1"])
-            assert_equal(data["var2"][n], sub["var2"])
-            assert_equal(data["var3"][:, n], sub["var3"])
-
-    def test_groupby_errors(self):
-        data = create_test_data()
-        with pytest.raises(TypeError, match=r"`group` must be"):
-            data.groupby(np.arange(10))
-        with pytest.raises(ValueError, match=r"length does not match"):
-            data.groupby(data["dim1"][:3])
-        with pytest.raises(TypeError, match=r"`group` must be"):
-            data.groupby(data.coords["dim1"].to_index())
-
-    def test_groupby_reduce(self):
-        data = Dataset(
-            {
-                "xy": (["x", "y"], np.random.randn(3, 4)),
-                "xonly": ("x", np.random.randn(3)),
-                "yonly": ("y", np.random.randn(4)),
-                "letters": ("y", ["a", "a", "b", "b"]),
-            }
-        )
-
-        expected = data.mean("y")
-        expected["yonly"] = expected["yonly"].variable.set_dims({"x": 3})
-        actual = data.groupby("x").mean(...)
-        assert_allclose(expected, actual)
-
-        actual = data.groupby("x").mean("y")
-        assert_allclose(expected, actual)
-
-        letters = data["letters"]
-        expected = Dataset(
-            {
-                "xy": data["xy"].groupby(letters).mean(...),
-                "xonly": (data["xonly"].mean().variable.set_dims({"letters": 2})),
-                "yonly": data["yonly"].groupby(letters).mean(),
-            }
-        )
-        actual = data.groupby("letters").mean(...)
-        assert_allclose(expected, actual)
-
-    def test_groupby_math(self):
-        def reorder_dims(x):
-            return x.transpose("dim1", "dim2", "dim3", "time")
-
-        ds = create_test_data()
-        ds["dim1"] = ds["dim1"]
-        for squeeze in [True, False]:
-            grouped = ds.groupby("dim1", squeeze=squeeze)
-
-            expected = reorder_dims(ds + ds.coords["dim1"])
-            actual = grouped + ds.coords["dim1"]
-            assert_identical(expected, reorder_dims(actual))
-
-            actual = ds.coords["dim1"] + grouped
-            assert_identical(expected, reorder_dims(actual))
-
-            ds2 = 2 * ds
-            expected = reorder_dims(ds + ds2)
-            actual = grouped + ds2
-            assert_identical(expected, reorder_dims(actual))
-
-            actual = ds2 + grouped
-            assert_identical(expected, reorder_dims(actual))
-
-        grouped = ds.groupby("numbers")
-        zeros = DataArray([0, 0, 0, 0], [("numbers", range(4))])
-        expected = (ds + Variable("dim3", np.zeros(10))).transpose(
-            "dim3", "dim1", "dim2", "time"
-        )
-        actual = grouped + zeros
-        assert_equal(expected, actual)
-
-        actual = zeros + grouped
-        assert_equal(expected, actual)
-
-        with pytest.raises(ValueError, match=r"incompat.* grouped binary"):
-            grouped + ds
-        with pytest.raises(ValueError, match=r"incompat.* grouped binary"):
-            ds + grouped
-        with pytest.raises(TypeError, match=r"only support binary ops"):
-            grouped + 1
-        with pytest.raises(TypeError, match=r"only support binary ops"):
-            grouped + grouped
-        with pytest.raises(TypeError, match=r"in-place operations"):
-            ds += grouped
-
-        ds = Dataset(
-            {
-                "x": ("time", np.arange(100)),
-                "time": pd.date_range("2000-01-01", periods=100),
-            }
-        )
-        with pytest.raises(ValueError, match=r"incompat.* grouped binary"):
-            ds + ds.groupby("time.month")
-
-    def test_groupby_math_virtual(self):
-        ds = Dataset(
-            {"x": ("t", [1, 2, 3])}, {"t": pd.date_range("20100101", periods=3)}
-        )
-        grouped = ds.groupby("t.day")
-        actual = grouped - grouped.mean(...)
-        expected = Dataset({"x": ("t", [0, 0, 0])}, ds[["t", "t.day"]])
-        assert_identical(actual, expected)
-
-    def test_groupby_nan(self):
-        # nan should be excluded from groupby
-        ds = Dataset({"foo": ("x", [1, 2, 3, 4])}, {"bar": ("x", [1, 1, 2, np.nan])})
-        actual = ds.groupby("bar").mean(...)
-        expected = Dataset({"foo": ("bar", [1.5, 3]), "bar": [1, 2]})
-        assert_identical(actual, expected)
-
-    def test_groupby_order(self):
-        # groupby should preserve variables order
-        ds = Dataset()
-        for vn in ["a", "b", "c"]:
-            ds[vn] = DataArray(np.arange(10), dims=["t"])
-        data_vars_ref = list(ds.data_vars.keys())
-        ds = ds.groupby("t").mean(...)
-        data_vars = list(ds.data_vars.keys())
-        assert data_vars == data_vars_ref
-        # coords are now at the end of the list, so the test below fails
-        # all_vars = list(ds.variables.keys())
-        # all_vars_ref = list(ds.variables.keys())
-        # self.assertEqual(all_vars, all_vars_ref)
-
     def test_resample_and_first(self):
         times = pd.date_range("2000-01-01", freq="6H", periods=10)
         ds = Dataset(
diff --git a/xarray/tests/test_groupby.py b/xarray/tests/test_groupby.py
