pandas SettingWithCopyWarning

[C-H-Simpson]

I get a warning

_catalogue.py:305: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

As far as I can tell, the output is as expected and this does not cause a problem.

[0xKoios]

The warning offers a suggestion to rewrite as follows:
df.loc[df['A'] > 2, 'B'] = new_val

[scotthosking]

I've fixed this warning but now get the following:

In [2]: bp.catalogue(Var=['tas','uas'], Experiment='historical', complete_var_set=True)

/Users/scott/miniconda3/lib/python3.6/site-packages/pandas/core/indexing.py:845: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
self.obj[key] = _infer_fill_value(value)
/Users/scott/miniconda3/lib/python3.6/site-packages/pandas/core/indexing.py:966: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
self.obj[item] = s