[BUG] Changing values at an index in list column is resulting in errors

[galipremsagar]

Describe the bug
When we try to modify values in list column using the user-facing __setitem__, there seems to be some failures.

Steps/Code to reproduce bug

In [1]: import cudf

In [2]: s = cudf.Series([[1, 2], [1], [2]])

In [3]: s
Out[3]: 
0    [1, 2]
1       [1]
2       [2]
dtype: list

In [4]: s[slice(0, 1, None)] = [3]
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
Input In [4], in <cell line: 1>()
----> 1 s[slice(0, 1, None)] = [3]

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/contextlib.py:79, in ContextDecorator.__call__.<locals>.inner(*args, **kwds)
     76 @wraps(func)
     77 def inner(*args, **kwds):
     78     with self._recreate_cm():
---> 79         return func(*args, **kwds)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/series.py:1095, in Series.__setitem__(self, key, value)
   1092 @_cudf_nvtx_annotate
   1093 def __setitem__(self, key, value):
   1094     if isinstance(key, slice):
-> 1095         self.iloc[key] = value
   1096     else:
   1097         self.loc[key] = value

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/contextlib.py:79, in ContextDecorator.__call__.<locals>.inner(*args, **kwds)
     76 @wraps(func)
     77 def inner(*args, **kwds):
     78     with self._recreate_cm():
---> 79         return func(*args, **kwds)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/series.py:147, in _SeriesIlocIndexer.__setitem__(self, key, value)
    142         value = value.astype(to_dtype)
    143         self._frame._column._mimic_inplace(
    144             self._frame._column.astype(to_dtype), inplace=True
    145         )
--> 147 self._frame._column[key] = value

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/column/lists.py:99, in ListColumn.__setitem__(self, key, value)
     97 else:
     98     raise ValueError(f"Can not set {value} into ListColumn")
---> 99 super().__setitem__(key, value)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/column/column.py:494, in ColumnBase.__setitem__(self, key, value)
    492 out: Optional[ColumnBase]  # If None, no need to perform mimic inplace.
    493 if isinstance(key, slice):
--> 494     out = self._scatter_by_slice(key, value_normalized)
    495 else:
    496     key = as_column(key)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/column/column.py:526, in ColumnBase._scatter_by_slice(self, key, value)
    524 if step == 1:
    525     if isinstance(value, cudf.core.scalar.Scalar):
--> 526         return self._fill(value, start, stop, inplace=True)
    527     else:
    528         return libcudf.copying.copy_range(
    529             value, self, 0, num_keys, start, stop, False
    530         )

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/column/column.py:340, in ColumnBase._fill(self, fill_value, begin, end, inplace)
    337     mask = create_null_mask(self.size, state=MaskState.ALL_VALID)
    338     self.set_base_mask(mask)
--> 340 libcudf.filling.fill_in_place(self, begin, end, slr.device_value)
    342 return self

File filling.pyx:31, in cudf._lib.filling.fill_in_place()

RuntimeError: cuDF failure at: /nvme/0/pgali/cudf/cpp/src/filling/fill.cu:214: In-place fill does not support variable-sized types.

In [5]: ps = s.to_pandas()

In [8]: ps[slice(0, 1, None)] = [[3]]

In [9]: ps
Out[9]: 
0    [3]
1    [1]
2    [2]
dtype: object

In [10]: s[slice(0, 1, None)] = [[3]]
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [10], in <cell line: 1>()
----> 1 s[slice(0, 1, None)] = [[3]]

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/contextlib.py:79, in ContextDecorator.__call__.<locals>.inner(*args, **kwds)
     76 @wraps(func)
     77 def inner(*args, **kwds):
     78     with self._recreate_cm():
---> 79         return func(*args, **kwds)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/series.py:1095, in Series.__setitem__(self, key, value)
   1092 @_cudf_nvtx_annotate
   1093 def __setitem__(self, key, value):
   1094     if isinstance(key, slice):
-> 1095         self.iloc[key] = value
   1096     else:
   1097         self.loc[key] = value

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/contextlib.py:79, in ContextDecorator.__call__.<locals>.inner(*args, **kwds)
     76 @wraps(func)
     77 def inner(*args, **kwds):
     78     with self._recreate_cm():
---> 79         return func(*args, **kwds)

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/series.py:147, in _SeriesIlocIndexer.__setitem__(self, key, value)
    142         value = value.astype(to_dtype)
    143         self._frame._column._mimic_inplace(
    144             self._frame._column.astype(to_dtype), inplace=True
    145         )
--> 147 self._frame._column[key] = value

File /nvme/0/pgali/envs/cudfdev/lib/python3.9/site-packages/cudf/core/column/lists.py:94, in ListColumn.__setitem__(self, key, value)
     92 if isinstance(value, cudf.Scalar):
     93     if value.dtype != self.dtype:
---> 94         raise TypeError("list nesting level mismatch")
     95 elif value is NA:
     96     value = cudf.Scalar(value, dtype=self.dtype)

TypeError: list nesting level mismatch

In [11]: 

Expected behavior
Match pandas behavior in this case.

Environment overview (please complete the following information)

• Environment location: [Bare-metal]
• Method of cuDF install: [from source]

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[galipremsagar]

Duplicate of #11721