I am trying to create a custom datetime class in python to support a time series model. After reviewing some of the existing python libraries I found that the pandas DatetimeIndex class provides much of the functionality I am looking for, but I would still like to add some methods for my needs. I have tried to subclass the DatetimeIndex class with a custom init constructor and then call the super init constructor, but I can't seem to get this to work. Has anyone done this? It would be great to get some insight on how to accomplish this.
This is about the simplest example I can think of. Here is a class defined in a module called time:
from pandas import DatetimeIndex
class DatetimeSub(DatetimeInex):
def __init___(initTime):
super().__init__(initTime)
When I test the class in the console with the following code:
import numpy as np
from time import DatetimeSub
testTime = TimeEfo2(np.arange('1985-01-01 12:00','1985-02-01 12:00', dtype="datetime64[D]"))
I get the following error:
TypeError: object.init() takes exactly one argument (the instance to initialize)
Which I don't understand because you can instantiate DatetimeIndex with a datetime64 array. This code works fine:
from pandas import DatetimeIndex
import numpy as np
dT = DatetimeIndex(np.arange('1985-01-01 12:00','1985-02-01 12:00', dtype="datetime64[D]"))
Thanks khuynh! That works. And how about if I wanted to create my own custom constructor such as:
from pandas import DatetimeIndex
import numpy as np
class DatetimeSub(DatetimeIndex):
def __init__(self, bgnTime, endTime, unit = 'D'):
# I am now constructing my numpy datetime64 array here:
initTime = np.arange(bgnTime, endTime, dtype="datetime64[{}]".format(unit))
# How do I call the super class to populate with the numpy array? This does not work:
super().__init__(initTime)
Thanks!
The first argument to a constructor is always self. So if you want to pass in initTime as a second argument, you'll need to add it to the constructor like so:
from pandas import DatetimeIndex
import numpy as np
class DatetimeSub(DatetimeIndex):
def __init__(self, initTime):
super().__init__()
dt = DatetimeIndex(np.arange('1985-01-01 12:00','1985-02-01 12:00', dtype="datetime64[D]"))
ds = DatetimeSub(np.arange('1985-01-01 12:00','1985-02-01 12:00', dtype="datetime64[D]"))
print(dt)
print(ds)
output:
DatetimeIndex(['1985-01-01', '1985-01-02', '1985-01-03', '1985-01-04',
'1985-01-05', '1985-01-06', '1985-01-07', '1985-01-08',
'1985-01-09', '1985-01-10', '1985-01-11', '1985-01-12',
'1985-01-13', '1985-01-14', '1985-01-15', '1985-01-16',
'1985-01-17', '1985-01-18', '1985-01-19', '1985-01-20',
'1985-01-21', '1985-01-22', '1985-01-23', '1985-01-24',
'1985-01-25', '1985-01-26', '1985-01-27', '1985-01-28',
'1985-01-29', '1985-01-30', '1985-01-31'],
dtype='datetime64[ns]', freq=None)
DatetimeSub(['1985-01-01', '1985-01-02', '1985-01-03', '1985-01-04',
'1985-01-05', '1985-01-06', '1985-01-07', '1985-01-08',
'1985-01-09', '1985-01-10', '1985-01-11', '1985-01-12',
'1985-01-13', '1985-01-14', '1985-01-15', '1985-01-16',
'1985-01-17', '1985-01-18', '1985-01-19', '1985-01-20',
'1985-01-21', '1985-01-22', '1985-01-23', '1985-01-24',
'1985-01-25', '1985-01-26', '1985-01-27', '1985-01-28',
'1985-01-29', '1985-01-30', '1985-01-31'],
dtype='datetime64[ns]', freq=None)