我尝试在日期列上合并两个数据框(尝试过类型为object
或datetime.date
),但未能得到所需的合并输出:
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
df1.month.dtype
=dtype('O')
和df2.month.dtype
=dtype('O')
,所以如果两者都是字符串类型,那么为什么会有影响呢? - muondate
、list
、set
和str
都是对象 - 参见这里。 - jezraelpd.to_datetime()
也没有帮助。 - muondtype
是对象,但type
不是。 - jezrael