为什么日期时间会自动更改为对象数据类型？

Question

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过滤时不知不觉地再次更改为对象。

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：类型错误：'NoneType' 对象不可订阅

预期结果：需要与其他行和列一起显示过滤后的列表

Answer 1

我想你需要 to_datetime 如果第一个数字是天，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 dt.floor 的时间并比较：

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]

为什么日期时间会自动更改为对象数据类型？

why date-time is automatically changed to the object datatype?

python

pandas

excel-automation