BUG: groupby.describe on a frame with duplicate column names · Issue #50806 · pandas-dev/pandas (original) (raw)

xref #46944

pd.set_option("display.max_columns", None)

df = DataFrame([[0, 1, 2, 3]])
df.columns = [0, 1, 2, 0]
gb = df.groupby(df[1])
print(gb.describe(percentiles=[]).to_string())
#       0                                                           2                        
#   count mean std  min  50%  max count mean std  min  50%  max count mean std  min  50%  max
# 1                                                                                          
# 1   1.0  0.0 NaN  0.0  0.0  0.0   1.0  3.0 NaN  3.0  3.0  3.0   1.0  2.0 NaN  2.0  2.0  2.0

With duplicate column names, describe only outputs the values for the first column. There should be two columns named 0 here. This issue occurs for any operation where the groupby code is using _selected_obj within the _group_selection_context.