python - nueva - insertar fila data frame pandas

los pandas se fusionan con el problema de la columna de fecha

Question

Estoy intentando fusionar dos dataframes en la columna de fecha (probándolos como tipo de object o datetime.date , pero no se obtienen los resultados de fusión deseados:

import pandas as pd
df1 =  pd.DataFrame({''amt'': {0: 1549367.9496070854,
      1: 2175801.78219801,
      2: 1915613.1629125737,
      3: 1703063.8323954903,
      4: 1770040.7987461537},
     ''month'': {0: ''2015-02-01'',
      1: ''2015-03-01'',
      2: ''2015-04-01'',
      3: ''2015-05-01'',
      4: ''2015-06-01''}})
print(df1)


        amt             month
    0   1.549368e+06    2015-02-01
    1   2.175802e+06    2015-03-01
    2   1.915613e+06    2015-04-01
    3   1.703064e+06    2015-05-01
    4   1.770041e+06    2015-06-01



df2 =  {''factor'': {datetime.date(2015, 2, 1): 1.0,
      datetime.date(2015, 3, 1): 1.0,
      datetime.date(2015, 4, 1): 1.0,
      datetime.date(2015, 5, 1): 1.0,
      datetime.date(2015, 6, 1): 0.99889679025914435},
     ''month'': {datetime.date(2015, 2, 1): datetime.date(2015, 2, 1),
      datetime.date(2015, 3, 1): datetime.date(2015, 3, 1),
      datetime.date(2015, 4, 1): datetime.date(2015, 4, 1),
      datetime.date(2015, 5, 1): datetime.date(2015, 5, 1),
      datetime.date(2015, 6, 1): datetime.date(2015, 6, 1)}}
df2 = pd.DataFrame(df2)
print(df2)

                factor      month
    2015-02-01  1.000000    2015-02-01
    2015-03-01  1.000000    2015-03-01
    2015-04-01  1.000000    2015-04-01
    2015-05-01  1.000000    2015-05-01
    2015-06-01  0.998897    2015-06-01


pd.merge(df2, df1, how=''outer'', on=''month'')

        factor       month            amt
    0   1.000000     2015-02-01      NaN
    1   1.000000     2015-03-01      NaN
    2   1.000000     2015-04-01      NaN
    3   1.000000     2015-05-01      NaN
    4   0.998897     2015-06-01      NaN
    5   NaN           2015-02-01    1.549368e+06
    6   NaN           2015-03-01    2.175802e+06
    7   NaN           2015-04-01    1.915613e+06
    8   NaN           2015-05-01    1.703064e+06
    9   NaN           2015-06-01    1.770041e+06

Answer 1

Creo que primero necesita convertir ambas columnas en to_datetime porque necesita los mismos dtypes :

df1.month = pd.to_datetime(df1.month)
df2.month = pd.to_datetime(df2.month)

print (pd.merge(df2, df1, how=''outer'', on=''month''))
     factor      month           amt
0  1.000000 2015-02-01  1.549368e+06
1  1.000000 2015-03-01  2.175802e+06
2  1.000000 2015-04-01  1.915613e+06
3  1.000000 2015-05-01  1.703064e+06
4  0.998897 2015-06-01  1.770041e+06

#convert to str date column
df2.month = df2.month.astype(str)

print (pd.merge(df2, df1, how=''outer'', on=''month''))
     factor       month           amt
0  1.000000  2015-02-01  1.549368e+06
1  1.000000  2015-03-01  2.175802e+06
2  1.000000  2015-04-01  1.915613e+06
3  1.000000  2015-05-01  1.703064e+06
4  0.998897  2015-06-01  1.770041e+06