如何将 python pandas 系列列附加到数据框？

Question

我是 python 熊猫的新手。 我有一个关于处理熊猫数据框的问题。 我使用 FRED (Federal Reserve Economic Data - St. Louis Fed) python api 来获取大数据。 以下是来源。

df_poverty = fred.search(search_str, order_by='title')  # returns pandas dataframe
mask_poverty = df_poverty.title == search_str  
df_poverty = df_poverty.loc[mask_poverty,['id']] 
if not df_poverty.empty:
   df_poverty_tmp = fred.get_series(df_poverty.iloc[0].id)  # returns another pandas dataframe
   print('******************')
   print(df_poverty.index)
   print('==================')
   print(df_poverty.head())
   print('==================')
   print(df_poverty_tmp.index)
   print('==================')
   print(df_poverty_tmp.head())

上面的代码打印以下结果。

******************
Index(['PPAAAR05000A156NCEN'], dtype='object', name='series id')
==================
                                      id
series id                               
PPAAAR05000A156NCEN  PPAAAR05000A156NCEN
==================
DatetimeIndex(['1989-01-01', '1990-01-01', '1991-01-01', '1992-01-01',
               '1993-01-01', '1994-01-01', '1995-01-01', '1996-01-01',
               '1997-01-01', '1998-01-01', '1999-01-01', '2000-01-01',
               '2001-01-01', '2002-01-01', '2003-01-01', '2004-01-01',
               '2005-01-01', '2006-01-01', '2007-01-01', '2008-01-01',
               '2009-01-01', '2010-01-01', '2011-01-01', '2012-01-01',
               '2013-01-01', '2014-01-01', '2015-01-01', '2016-01-01',
               '2017-01-01', '2018-01-01'],
              dtype='datetime64[ns]', freq=None)
==================
1989-01-01    17.9
1990-01-01     NaN
1991-01-01     NaN
1992-01-01     NaN
1993-01-01    18.9
dtype: float64

我的目标结果格式是具有时间序列索引的特征矩阵，如下所示，

1989-01-01     PPAAAR05000A156NCEN            17.9
1990-01-01     PPAAAR05000A156NCEN            NaN
1991-01-01     PPAAAR05000A156NCEN            NaN
1992-01-01     PPAAAR05000A156NCEN            NaN
1993-01-01     PPAAAR05000A156NCEN            18.9

我做了python代码，但结果并不令人满意，

> df_poverty_tmp.append(df_poverty)

                        0                   id
1989-01-01 00:00:00  17.7                  NaN
1990-01-01 00:00:00   NaN                  NaN
1991-01-01 00:00:00   NaN                  NaN
1992-01-01 00:00:00   NaN                  NaN
1993-01-01 00:00:00  18.8                  NaN
1994-01-01 00:00:00   NaN                  NaN
1995-01-01 00:00:00  17.6                  NaN
1996-01-01 00:00:00  16.7                  NaN
1997-01-01 00:00:00  16.2                  NaN
1998-01-01 00:00:00  15.7                  NaN
PPAAAL01000A156NCEN   NaN  PPAAAL01000A156NCEN

我想知道如何将 Pandas 系列值插入到 Pandas 数据框列的中间。 任何答复将不胜感激。

== 更新部分

我添加几行以供您理解。

df_poverty = df_poverty.loc[mask_poverty,['id', 'title', 'frequency_short', 'seasonal_adjustment_short']]
print(df_poverty)

打印行显示以下结果

                                      id  title   frequency_short seasonal_adjustment_short
series id                                                           
PPAAAK02000A156NCEN  PPAAAK02000A156NCEN  test1           M                 NSA

然后我预期的功能如下所示，

time                    id             title   frequency_short   value

1989-01-01     PPAAAR05000A156NCEN     test1         M            17.9
1990-01-01     PPAAAR05000A156NCEN     test1         M             NaN
1991-01-01     PPAAAR05000A156NCEN     test1         M             NaN
1992-01-01     PPAAAR05000A156NCEN     test1         M             NaN
1993-01-01     PPAAAR05000A156NCEN     test1         M             18.9

Answer 1

由于您有重复的列（两列内容相同），我建议您删除一列。

df_poverty = df_poverty.drop("series id", 1)
df_poverty["time"] = DatetimeIndex.strftime(%Y-%m-%d)