To learn about the datetime64 data type, start a Python shell and import NumPy as follows:

$ python
>>> import numpy as np

Create a datetime64 from a string (you can use another date if you like):

>>> np.datetime64('2015-04-22')
numpy.datetime64('2015-04-22')

In the preceding code, we created a datetime64 for April 22, 2015, which happens to be Earth Day. We used the YYYY-MM-DD format, where Y corresponds to the year, M corresponds to the month, and D corresponds to the day of the month. NumPy uses the ISO 8601 standard (see http://en.wikipedia.org/wiki/ISO_8601). This is an international standard to represent dates and times. ISO 8601 allows the YYYY-MM-DD, YYYY-MM, and YYYYMMDD formats. Check for yourself, as follows:

>>> np.datetime64('2015-04-22')
numpy.datetime64('2015-04-22')
>&gt...