Added repr string for Grouper and TimeGrouper

Author: tp

pandas/core/groupby.py

@@ -333,6 +333,17 @@ def _set_grouper(self, obj, sort=False):
     def groups(self):
         return self.grouper.groups
 
+    _attributes = dict(key=None, level=None, freq=None, axis=0,
+                       sort=False)
+
+    def __repr__(self):
+        defaults = self._attributes
+        attrs = {k: v for k, v in self.__dict__.items()
+                 if k in defaults and v != defaults[k]}
+        attrs = ", ".join("{}={!r}".format(k, v) for k, v in attrs.items())
+        cls_name = self.__class__.__name__
+        return "{}({})".format(cls_name, attrs)
+
 
 class GroupByPlot(PandasObject):
     """

pandas/core/resample.py

@@ -1028,7 +1028,7 @@ def __init__(self, freq='Min', closed=None, label=None, how='mean',
                  convention=None, base=0, **kwargs):
         freq = to_offset(freq)
 
-        end_types = set(['M', 'A', 'Q', 'BM', 'BA', 'BQ', 'W'])
+        self._end_types = end_types = {'M', 'A', 'Q', 'BM', 'BA', 'BQ', 'W'}
         rule = freq.rule_code
         if (rule in end_types or
                 ('-' in rule and rule[:rule.find('-')] in end_types)):
@@ -1286,6 +1286,29 @@ def _get_period_bins(self, ax):
 
         return binner, bins, labels
 
+    # _attributes is used in __repr__below
+    _attributes = Grouper._attributes.copy()
+    _attributes.update(freq='Min', how='mean', nperiods=None, axis=0,
+                       fill_method=None, limit=None, loffset=None,
+                       kind=None, convention='e', base=0, sort=True)
+
+    def __repr__(self):
+        defaults = self._attributes.copy()
+        end_types = self._end_types
+        rule = self.freq.rule_code
+        if (rule in end_types or
+                ('-' in rule and rule[:rule.find('-')] in end_types)):
+            defaults.update(closed='right', label='right')
+        else:
+            defaults.update(closed='left', label='left')
+
+        attrs = {k: v for k, v in self.__dict__.items()
+                 if k in defaults and v != defaults[k]}
+        attrs['freq'] = attrs['freq'].freqstr
+        attrs = ", ".join("{}={!r}".format(k, v) for k, v in attrs.items())
+        cls_name = self.__class__.__name__
+        return "{}({})".format(cls_name, attrs)
+
 
 def _take_new_index(obj, indexer, new_index, axis=0):
     from pandas.core.api import Series, DataFrame

pandas/tests/groupby/test_groupby.py

@@ -130,6 +130,17 @@ def test_grouper_index_types(self):
             df.index = list(reversed(df.index.tolist()))
             df.groupby(list('abcde')).apply(lambda x: x)
 
+    def test_grouper_repr(self):
+        # Added in GH17727
+        result = repr(pd.Grouper(key='A'))
+        assert result == "Grouper(key='A')"
+
+        result = repr(pd.Grouper(key='key', freq='50Min', label='right'))
+        cls_name_result, attrib_result = result.split('(', maxsplit=1)
+        attrib_result = set(attrib_result.rstrip(')').split(', '))
+        assert cls_name_result == 'TimeGrouper'
+        assert attrib_result == {"freq='50T'", "key='key'", "label='right'"}
+
     def test_grouper_multilevel_freq(self):
 
         # GH 7885

pandas/tests/test_resample.py

@@ -3157,6 +3157,14 @@ def setup_method(self, method):
         self.ts = Series(np.random.randn(1000),
                          index=date_range('1/1/2000', periods=1000))
 
+    def test_timegrouper_repr(self):
+        # Added in GH17727
+        result = repr(TimeGrouper(key='key', freq='50Min', label='right'))
+        cls_name_result, attrib_result = result.split('(', maxsplit=1)
+        attrib_result = set(attrib_result.rstrip(')').split(', '))
+        assert cls_name_result == 'TimeGrouper'
+        assert attrib_result == {"freq='50T'", "key='key'", "label='right'"}
+
     def test_apply(self):
         with tm.assert_produces_warning(FutureWarning,
                                         check_stacklevel=False):