从时间索引的熊猫数据帧中获取两个时间戳内特定时间的值

Question

I have the following pandas dataframe df:

                     C1  C2   C3
Date                             
2000-01-01 00:00:00   2  175  160
2000-01-01 01:00:00   4  192  164
2000-01-01 02:00:00   6  210  189
2000-01-01 03:00:00   8  217  199
2000-01-01 04:00:00  10  176  158

from which I need to get the value of C1, C2 and C3 for a specific datetime:

import datetime
my_specific_time = str(datetime.datetime(2000, 1, 1, 1, 0, 0))
print(df['C1'].loc[mytime]) # prints 4

The problem is that I can only get values for the dates stored in the df. For example, getting the value of C1 for time 2000-01-01 01:30:00 is not possible unless I resample my dataframe:

upsampled = df.resample('30min').ffill()
my_specific_time = str(datetime.datetime(2000, 1, 1, 1, 30, 0))
print(upsampled['C1'].loc[mytime]) # again prints 4

Please note that all the value of C1 between timespan of 2000-01-01 01:00:00 and 2000-01-01 02:00:00 is 4 . Now the problem is that my_specific_time can be any random time and I would need to resample df using small enough values to be able to get the value for. I think this is not the best solution for this problem.

While looking for possible solutions I only came across time spans in pandas but I did not quite understand how possibly I can use it in my problem.

Answer 1

Use DataFrame.asof method:

print(df['C1'].asof(my_specific_time))

4