Convert datetime.datetime object to days since epoch in Python

问题

I've got a pandas.Series object that might look like this:

import pandas as pd
myVar = pd.Series(["VLADIVOSTOK 690090", "MAHE", NaN, NaN, "VLADIVOSTOK 690090", "2000-07-01 00:00:00"])

myVar[5] is parsed as a datetime.datetime object when the data is read into Python via pandas. I'm assuming that converting this value to the number of days since epoch (36708) isn't difficult at all. I'm just new to Python and don't know how to do it. Thanks in advance!

回答1:

myVar = pd.Series(["VLADIVOSTOK 690090", "MAHE", "NaN", "NaN", "VLADIVOSTOK 690090", "2000-07-01 00:00:00"])

myVar[5] = pd.to_datetime(myVar[5]) - pd.datetime(1970,1,1)

print(myVar)
0     VLADIVOSTOK 690090
1                   MAHE
2                    NaN
3                    NaN
4     VLADIVOSTOK 690090
5    11139 days 00:00:00
dtype: object

回答2:

I'm not sure where you're getting 36,708 days since the epoch (it's only been 16,644 days since January 1, 1970), but datetime.timedelta objects (used in date arithmetic) have a days attribute:

>>> import datetime
>>> (datetime.datetime.utcnow() - datetime.datetime(1970,1,1)).days
16644

回答3:

You can convert this to seconds since epoch first, then divide it out by the amount of seconds in a day (86,400 seconds in a day). Please note the integer division here - will not return a float.

from datetime import datetime
now = datetime.now()
seconds = now.strftime("%s") # seconds since epoch
days = int(seconds) / 86400 # days since epoch

I added the import and now as an example of a datetime object I can play with.

来源：https://stackoverflow.com/questions/31687420/convert-datetime-datetime-object-to-days-since-epoch-in-python