python - 为什么日期时间会自动更改为对象数据类型？

Question

过滤时需要将对象类型转换为日期时间并使用转换后的日期时间在不知不觉中再次更改为对象。

msft['Tested On'] = pd.to_datetime(msft['Tested On'])
msft['Tested On'].dt.date
df = msft[msft['Tested On'] == '2018-02-02']

实际结果：TypeError: 'NoneType' object is not subscriptable

预期结果：还需要显示过滤后的列表以及其他行和列

Answer 1

我认为您需要to_datetime，如果第一个数字是天，请添加参数dayfirst=True：

print (msft)
  Title plan     run   status           Tested On
0     A   P0      P0   Passed  11/08/2018 8:42 AM
1     B   P0      P0   Failed  12/08/2018 8:42 AM
2     C    -  Canary   Passed  10/08/2018 8:42 AM
3     D    -  Sanity  Blocked  11/08/2018 8:42 AM

msft['Tested On'] = pd.to_datetime(msft['Tested On'], dayfirst=True)
print (msft)
  Title plan     run   status           Tested On
0     A   P0      P0   Passed 2018-08-11 08:42:00
1     B   P0      P0   Failed 2018-08-12 08:42:00
2     C    -  Canary   Passed 2018-08-10 08:42:00
3     D    -  Sanity  Blocked 2018-08-11 08:42:00

然后删除时间dt.floor并进行比较：

df = msft[msft['Tested On'].dt.floor('d') == '2018-08-11']
print (df)
  Title plan     run   status           Tested On
0     A   P0      P0   Passed 2018-08-11 08:42:00
3     D    -  Sanity  Blocked 2018-08-11 08:42:00

详情：

print (msft['Tested On'].dt.floor('d'))
0   2018-08-11
1   2018-08-12
2   2018-08-10
3   2018-08-11
Name: Tested On, dtype: datetime64[ns]