AttributeError: module 'pandas.core.common' has no attribute '_unpickle_array'

[simonjayhawkins]

mypy errors

pandas\core\frame.py:2742:23: error: Module has no attribute "_unpickle_array"  [attr-defined]
pandas\core\frame.py:2744:17: error: Module has no attribute "_unpickle_array"  [attr-defined]
pandas\core\frame.py:2751:17: error: Module has no attribute "_unpickle_array"  [attr-defined]
pandas\core\frame.py:2752:51: error: Module has no attribute "_unpickle_array"  [attr-defined]
pandas\core\frame.py:2757:45: error: Module has no attribute "_unpickle_array"  [attr-defined]

>>> import pandas as pd
>>>
>>> pd.__version__
'0.26.0.dev0+521.g93183bab1'
>>>
>>> df = pd.DataFrame()
>>>
>>> state = df.__getstate__()
>>>
>>> state
{'_data': BlockManager
Items: Index([], dtype='object')
Axis 1: Index([], dtype='object'), '_typ': 'dataframe', '_metadata': []}
>>>
>>> df._unpickle_frame_compat(state)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\simon\pandas-simonjayhawkins\pandas\core\frame.py", line 2717, in _unpickle_frame_compat
    columns = com._unpickle_array(cols)
AttributeError: module 'pandas.core.common' has no attribute '_unpickle_array'
>>>

we don't have any tests hitting DataFrame._unpickle_frame_compat or DataFrame._unpickle_matrix_compat

pandas/pandas/core/frame.py

Lines 2707 to 2738 in f625730

	# ----------------------------------------------------------------------
	# Picklability
	# legacy pickle formats
	def _unpickle_frame_compat(self, state): # pragma: no cover
	if len(state) == 2: # pragma: no cover
	series, idx = state
	columns = sorted(series)
	else:
	series, cols, idx = state
	columns = com._unpickle_array(cols)
	index = com._unpickle_array(idx)
	self._data = self._init_dict(series, index, columns, None)
	def _unpickle_matrix_compat(self, state): # pragma: no cover
	# old unpickling
	(vals, idx, cols), object_state = state
	index = com._unpickle_array(idx)
	dm = DataFrame(vals, index=index, columns=com._unpickle_array(cols), copy=False)
	if object_state is not None:
	ovals, _, ocols = object_state
	objects = DataFrame(
	ovals, index=index, columns=com._unpickle_array(ocols), copy=False
	)
	dm = dm.join(objects)
	self._data = dm._data

can this code be removed?

[jbrockmendel]

Looks like there exists such a function in io.pickle. I'd be pretty happy to see this untested code removed

[simonjayhawkins]

the one in io.pickle is preceded with # compat with sparse pickle / unpickle

[simonjayhawkins]

also in NDFrame.setstate there is a self._unpickle_panel_compat(state) which seems iffy. so I think NDFrame.setstate needs a bit of a clean.