How to properly add hours to a pandas.tseries.index.DatetimeIndex?

Question:

I have a normal df.index that I would like to add some hours to it.

In [1]: test[1].index
Out[2]: 
<class 'pandas.tseries.index.DatetimeIndex'>
[2010-03-11, ..., 2014-08-14]
Length: 52, Freq: None, Timezone: None

This is how the first element looks like:

In [1]: test[1].index[0]
Out[2]: Timestamp('2010-03-11 00:00:00')

So I try this to add the hours:

In [1]: test[1].index[0] + pd.tseries.timedeltas.to_timedelta(16, unit='h')

However I get this:

Out[2]: Timestamp('2010-03-11 00:00:00.000000016')

But I would like to get this:

Out[2]: Timestamp('2010-03-11 16:00:00')

What I am missing?. The enviroment is Anaconda (latest) Python 2.7.7, iPython 2.2

Thanks a lot

Asked By: hernanavella

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Source

Answers:

You can use pd.DateOffset:

test[1].index + pd.DateOffset(hours=16)

pd.DateOffset accepts the same keyword arguments as dateutil.relativedelta.

The problem you encountered was due to this bug which has been fixed in Pandas version 0.14.1:

In [242]: pd.to_timedelta(16, unit='h')
Out[242]: numpy.timedelta64(16,'ns')

If you upgrade, your original code should work.

Answered By: unutbu

Example of adding and subtracting time from a given datatime column in a given data frame.: using pd.Dateoffset()

 for index,row in insulin_dfs.iterrows():
        tm = row['date_time']
        print("Original Start Time :                  " + str(tm))
        start_time = tm + pd.DateOffset(minutes=-30)
        print("30 minutes prior Start Time :          " + str(start_time))
        end_time = tm + pd.DateOffset(hours=2)
        print("2 hours , 30 minutes from original Time" + str(end_time))
        break
output: 30 minutes prior to original time, and 2 hours after the time picked.

enter image description here

Note:
You can use the + for adding time to existing time and - for subtracting
time. you can pass multiple parameters simultaneously.

enter image description here

Answered By: Arpan Saini