python - 包含 pandas 数据框中单个元素列表的正确列

Question

我有以下内容。数据框:

      a_name  Season    yl
yl
4.939  cherka  2000.0  [4.939]
4.441  cherka  2001.0  [4.441]
4.320  cherka  2002.0   [4.32]
3.718  cherka  2003.0  [3.718]
4.533  cherka  2004.0  [4.533]

如何将其转换为:

      a_name  Season    yl
yl
4.939  cherka  2000.0  4.939
4.441  cherka  2001.0  4.441
4.320  cherka  2002.0  4.32
3.718  cherka  2003.0  3.718
4.533  cherka  2004.0  4.533

我通过这样做得到了它:

df.groupby(['a_name', 'Season', 'yl'])['yl'].unique().reset_index(level=[0,1])

Answer 1

扩展我的评论，使用.str[0]:

df

       a_name  Season       yl
yl                            
4.939  cherka  2000.0  [4.939]
4.441  cherka  2001.0  [4.441]
4.320  cherka  2002.0   [4.32]
3.718  cherka  2003.0  [3.718]
4.533  cherka  2004.0  [4.533]

df['yl'] = df['yl'].str[0]
df

       a_name  Season     yl
yl                          
4.939  cherka  2000.0  4.939
4.441  cherka  2001.0  4.441
4.320  cherka  2002.0  4.320
3.718  cherka  2003.0  3.718
4.533  cherka  2004.0  4.533

<小时/>

您可以选择使用分配 ( piRsquared's suggestion ) 创建副本:

df_new = df.assign(df['yl'].str[0])

df_new

       a_name  Season     yl
yl                          
4.939  cherka  2000.0  4.939
4.441  cherka  2001.0  4.441
4.320  cherka  2002.0  4.320
3.718  cherka  2003.0  3.718
4.533  cherka  2004.0  4.533