Converting between datetime, Timestamp and datetime64

Question

How do I convert a numpy.datetime64 object to a datetime.datetime (or Timestamp)?

In the following code, I create a datetime, timestamp and datetime64 objects.

import datetime import numpy as np import pandas as pd dt = datetime.datetime(2012, 5, 1) # A strange way to extract a Timestamp object, there's surely a better way? ts = pd.DatetimeIndex([dt])[0] dt64 = np.datetime64(dt)  In [7]: dt Out[7]: datetime.datetime(2012, 5, 1, 0, 0)  In [8]: ts Out[8]: <Timestamp: 2012-05-01 00:00:00>  In [9]: dt64 Out[9]: numpy.datetime64('2012-05-01T01:00:00.000000+0100') 

Note: it's easy to get the datetime from the Timestamp:

In [10]: ts.to_datetime() Out[10]: datetime.datetime(2012, 5, 1, 0, 0) 

But how do we extract the datetime or Timestamp from a numpy.datetime64 (dt64)?

.

Update: a somewhat nasty example in my dataset (perhaps the motivating example) seems to be:

dt64 = numpy.datetime64('2002-06-28T01:00:00.000000000+0100') 

which should be datetime.datetime(2002, 6, 28, 1, 0), and not a long (!) (1025222400000000000L)...

Answer 1

You can just use the pd.Timestamp constructor. The following diagram may be useful for this and related questions.

Answer 2

Welcome to hell.

You can just pass a datetime64 object to pandas.Timestamp:

In [16]: Timestamp(numpy.datetime64('2012-05-01T01:00:00.000000')) Out[16]: <Timestamp: 2012-05-01 01:00:00> 

I noticed that this doesn't work right though in NumPy 1.6.1:

numpy.datetime64('2012-05-01T01:00:00.000000+0100') 

Also, pandas.to_datetime can be used (this is off of the dev version, haven't checked v0.9.1):

In [24]: pandas.to_datetime('2012-05-01T01:00:00.000000+0100') Out[24]: datetime.datetime(2012, 5, 1, 1, 0, tzinfo=tzoffset(None, 3600))