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