python - How to add/subtract time (hours, minutes, etc.) from a Pandas DataFrame.Index whos objects are of type datetime.time?

75
votes

I've got a DataFrame who's index is just datetime.time and there's no method in DataFrame.Index and datetime.time to shift the time. datetime.time has replace but that'll only work on individual items of the Series?

Here's an example of the index used:

In[526]:  dfa.index[:5]
Out[526]: Index([21:12:19, 21:12:20, 21:12:21, 21:12:21, 21:12:22], dtype='object')

In[527]:  type(dfa.index[0])
Out[527]: datetime.time
3
pythondatetimetimepandas
stackoverflow.com/questions/19820280/… - Liam Foley
What is the output of type(df.index)? - Mostafa Mahmoud
@MostafaMahmoud pandas.core.index.Index but if I type(df.index[0]) that is datetime.time. - Cameron Stark
@DreamAwake Make use of pandas.Timestamp() to convert your current index to a timestamp index and then do whatever you want with it. - Mostafa Mahmoud

3 Answers

97
votes

Liam's link looks great, but also check out pandas.Timedelta - looks like it plays nicely with NumPy's and Python's time deltas.

https://pandas.pydata.org/pandas-docs/stable/timedeltas.html

pd.date_range('2014-01-01', periods=10) + pd.Timedelta(days=1)
2
votes

This one worked for me:

>> print(df)
                          TotalVolume  Symbol
2016-04-15 09:00:00       108400       2802.T
2016-04-15 09:05:00       50300        2802.T

>> print(df.set_index(pd.to_datetime(df.index.values) - datetime(2016, 4, 15)))

             TotalVolume  Symbol
09:00:00     108400       2802.T
09:05:00     50300        2802.T
0
votes

The Philippe solution but cleaner:

My subtraction data is: '2018-09-22T11:05:00.000Z'

import datetime
import pandas as pd

df_modified = pd.to_datetime(df_reference.index.values) - datetime.datetime(2018, 9, 22, 11, 5, 0)