Converting String To Date In Numpy Unpack

I'm learning how to extract data from links and then proceeding to graph them. For this tutorial, I was using the yahoo dataset of a stock. The code is as follows import matplotli

Solution 1:

With a guess as to the csv format, I can use the numpy 'native' datetime dtype:

In [183]: txt = ['2020-10-23 1 2.3']*3                                                                               
In [184]: txt                                                                                                        
Out[184]: ['2020-10-23 1 2.3', '2020-10-23 1 2.3', '2020-10-23 1 2.3']

If I let genfromtxt do its own dtype conversions:

In [187]: np.genfromtxt(txt, dtype=None, encoding=None)                                                              
Out[187]: 
array([('2020-10-23', 1, 2.3), ('2020-10-23', 1, 2.3),
       ('2020-10-23', 1, 2.3)],
      dtype=[('f0', '<U10'), ('f1', '<i8'), ('f2', '<f8')])

the date column is rendered as a string.

If I specify a datetime64 format:

In [188]: np.array('2020-10-23', dtype='datetime64[D]')                                                              
Out[188]: array('2020-10-23', dtype='datetime64[D]')

In [189]: np.genfromtxt(txt, dtype=['datetime64[D]',int,float], encoding=None)                                       
Out[189]: 
array([('2020-10-23', 1, 2.3), ('2020-10-23', 1, 2.3),
       ('2020-10-23', 1, 2.3)],
      dtype=[('f0', '<M8[D]'), ('f1', '<i8'), ('f2', '<f8')])

This date appears to work in plt

In [190]: plt.plot_date(_['f0'], _['f1'])       

I used genfromtxt because I'm more familiar with its ability to handle dtypes.