Find closest row of DataFrame to given time in Pandas

Question

I have a Pandas dataframe which is indexed by a DatetimeIndex:

DatetimeIndex: 53732 entries, 1993-01-07 12:23:5         


        

Answer 1

I think you can try DatetimeIndex.asof to find the most recent label up to and including the input. Then use the returned datetime to select the appropriate row. If you only need values for a particular column, Series.asof exists and combines the two steps above into one.

This assumes you want the closest datetime. If you don't care about the date and just want the same time every day, use at_time in DataFrame.

Follow up:

Edit: false alarm, I had an older version locally. The latest on master should work with np.abs.

In [10]: np.abs(df.time - image_time)
Out[10]: 
0    27 days, 13:39:02
1    26 days, 13:39:02
2    25 days, 13:39:02
3    24 days, 13:39:02
4    23 days, 13:39:02
5    22 days, 13:39:02

Also just to clarify:

aeronet.index - image_time doesn't work because subtraction on Index is a set difference (back in the day Index used to be constrained to be unique).