Asked By – LLaP
I have created a TimeSeries in pandas:
In : from datetime import datetime In : dates = [datetime(2011, 1, 2), datetime(2011, 1, 5), datetime(2011, 1, 7), .....: datetime(2011, 1, 8), datetime(2011, 1, 10), datetime(2011, 1, 12)] In : ts = Series(np.random.randn(6), index=dates) In : ts Out: 2011-01-02 0.690002 2011-01-05 1.001543 2011-01-07 -0.503087 2011-01-08 -0.622274 2011-01-10 -0.921169 2011-01-12 -0.726213
I’m following on the example from ‘Python for Data Analysis’ book.
In the following paragraph, the author checks the index type:
In : ts.index.dtype Out: dtype('datetime64[ns]')
When I do exactly the same operation in the console I get:
What is the difference between two types
And why do I get a different type?
Now we will see solution for issue: Difference between data type ‘datetime64[ns]’ and ‘
datetime64[ns] is a general dtype, while
<M8[ns] is a specific dtype. General dtypes map to specific dtypes, but may be different from one installation of NumPy to the next.
On a machine whose byte order is little endian, there is no difference between
In : np.dtype('datetime64[ns]') == np.dtype('<M8[ns]') Out: True
However, on a big endian machine,
np.dtype('datetime64[ns]') would equal
datetime64[ns] maps to either
>M8[ns] depending on the endian-ness of the machine.
There are many other similar examples of general dtypes mapping to specific dtypes:
int64 maps to
int maps to either
depending on the bit architecture of the OS and how NumPy was compiled.
Apparently, the repr of the datetime64 dtype has change since the time the book was written to show the endian-ness of the dtype.