BUG: Include "dropna" in Grouper._attributes

All this changes I think is that now `dropna` is included in the `__repr__` output. See #46258 for more discussion. And move dropna up out of the "generated" attribute section into the "source" attribute section in the __init__

Author: NickCrews

doc/source/whatsnew/v1.4.3.rst

@@ -24,7 +24,7 @@ Fixed regressions
 
 Bug fixes
 ~~~~~~~~~
--
+- Include ``dropna`` in ``__repr__`` of a :class:`Grouper` (:issue:`46754`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/groupby/grouper.py

@@ -263,7 +263,7 @@ class Grouper:
  _gpr_index: Index | None
  _grouper: Index | None
 
- _attributes: tuple[str, ...] = ("key", "level", "freq", "axis", "sort")
+ _attributes: tuple[str, ...] = ("key", "level", "freq", "axis", "sort", "dropna")
 
  def __new__(cls, *args, **kwargs):
  if kwargs.get("freq") is not None:
@@ -287,6 +287,7 @@ def __init__(
  self.freq = freq
  self.axis = axis
  self.sort = sort
+ self.dropna = dropna
 
  self.grouper = None
  self._gpr_index = None
@@ -295,7 +296,6 @@ def __init__(
  self.binner = None
  self._grouper = None
  self._indexer = None
- self.dropna = dropna
 
  @final
  @property

pandas/tests/groupby/test_groupby.py

@@ -31,7 +31,7 @@
 def test_repr():
  # GH18203
  result = repr(Grouper(key="A", level="B"))
- expected = "Grouper(key='A', level='B', axis=0, sort=False)"
+ expected = "Grouper(key='A', level='B', axis=0, sort=False, dropna=True)"
  assert result == expected
 
 

pandas/tests/resample/test_time_grouper.py

@@ -274,7 +274,7 @@ def test_repr():
 
  result = repr(Grouper(key="A", freq="H", origin="2000-01-01"))
  expected = (
- "TimeGrouper(key='A', freq=<Hour>, axis=0, sort=True, "
+ "TimeGrouper(key='A', freq=<Hour>, axis=0, sort=True, dropna=True "
  "closed='left', label='left', how='mean', "
  "convention='e', origin=Timestamp('2000-01-01 00:00:00'))"
  )