how can get difference between a defined date and the dates from a csv file python

I have a list of dates and I want to get a difference from a defined one(I mean days) and append days calculated in a new column

from datetime import date, datetime
import pandas as pd

df = pd.read_csv("date.csv", parse_dates = ["dates"])

#a date to substact dates in csv
defined_date = date(2020,12,25)

#a list of dates from a csv file
csv_dates = df.dates

diff = [defined_date  - csv_dates]
print(diff)

I get TypeError: unsupported operand type(s) for -: 'DatetimeArray' and 'datetime.date'

Now how can I read the dates in csv file in the same format as the defined date is there a way to do so

#How to change a list of dates from a csv file to date datatype
csv_dates = df.dates

Answer

It is happening because you are trying to subtract array(series) from defined_date. Which doesn’t work like that. You need to iterate over your csv_dates series and add differences to the new column.

dates_diff = []
for d in csv_dates:
    dates_diff.append(d.date() - defined_date)

df['diff'] = dates_diff