groupby repr

xarray/core/groupby.py

@@ -9,6 +9,7 @@
 from .arithmetic import SupportsArithmetic
 from .common import ImplementsArrayReduce, ImplementsDatasetReduce
 from .concat import concat
+from .formatting import format_array_flat
 from .options import _get_keep_attrs
 from .pycompat import integer_types
 from .utils import (
@@ -158,6 +159,15 @@ def ndim(self):
     def values(self):
         return range(self.size)
 
+    @property
+    def shape(self):
+        return (self.size,)
+
+    def __getitem__(self, key):
+        if isinstance(key, tuple):
+            key = key[0]
+        return self.values[key]
+
 
 def _ensure_1d(group, obj):
     if group.ndim != 1:
@@ -383,6 +393,14 @@ def __len__(self):
     def __iter__(self):
         return zip(self._unique_coord.values, self._iter_grouped())
 
+    def __repr__(self):
+        return "%s, grouped over %r \n%r groups with labels %s" % (
+            self.__class__.__name__,
+            self._unique_coord.name,
+            self._unique_coord.size,
+            ", ".join(format_array_flat(self._unique_coord, 30).split()),
+        )
+
     def _get_index_and_items(self, index, grouper):
         from .resample_cftime import CFTimeGrouper
 

xarray/tests/test_groupby.py

@@ -202,4 +202,28 @@ def test_da_groupby_assign_coords():
     assert_identical(expected, actual2)
 
 
+test_da = xr.DataArray(
+    np.random.randn(10, 20, 6),
+    dims=["x", "y", "z"],
+    coords={"z": ["a", "b", "c", "a", "b", "c"], "x": [1, 1, 1, 2, 2, 3, 4, 5, 3, 4]},
+)
+
+
+@pytest.mark.parametrize("dim", ["x", "y", "z"])
+@pytest.mark.parametrize("obj", [test_da, test_da.to_dataset(name="a")])
+def test_groupby_repr(obj, dim):
+
+    actual = repr(obj.groupby(dim))
+    expected = "%sGroupBy" % obj.__class__.__name__
+    expected += ", grouped over %r " % dim
+    expected += "\n%r groups with labels " % (len(np.unique(obj[dim])))
+    if dim == "x":
+        expected += "1, 2, 3, 4, 5"
+    elif dim == "y":
+        expected += "0, 1, 2, 3, 4, 5, ..., 15, 16, 17, 18, 19"
+    elif dim == "z":
+        expected += "'a', 'b', 'c'"
+    assert actual == expected
+
+
 # TODO: move other groupby tests from test_dataset and test_dataarray over here