Converting "Days" from Timedelta object to regular object

Question

I'm trying to merge the two data frames below on "day", but the time delta object is preventing this. My understanding is that I should be able to then do something like print(df['day'].days) and get the actual day without the "days."

df1

import pandas as pd
from itertools import product

missing = pd.DataFrame(product(range(1,31), range(1,5)), columns=['date','time_of_day'])
missing = pd.concat([missing.assign(pid=_id) for _id in vec], ignore_index=True)
#pd.DataFrame(product([vec, range(1,31), range(1,5)], names=['pid','day','time_of_day']))

missing.pid = missing.pid.astype(str)

df 2

from timedelta import date

def random_dates(start, end, n=12):

    start_u = start.value//10**9
    end_u = end.value//10**9

    return pd.to_datetime(np.random.randint(start_u, end_u, n), unit='s')

start = pd.to_datetime('2015-01-01')
end = pd.to_datetime('2018-01-01')
random_dates(start, end)

df = pd.DataFrame({'datestamp':random_dates(start, end)})
df['date'] = pd.to_datetime(df['datestamp']).dt.date
df['time'] = pd.to_datetime(df['datestamp']).dt.time


df = pd.concat([df.assign(pid=_id) for _id in vec], ignore_index=True)

df['last'] = df\
.sort_values('date')\
.groupby('pid')['date']\
.transform('last')

df['days'] = df['last'] - df['date']
df
df['days'].days #doesn't work

merging

missing.merge(df, how = 'left', on = ['pid', 'day'])

corresponding error

Answer 1

so this would convert to days as a non-timedelta object:

def get_custom_str_time(x): return math.floor(x.total_seconds()/(3600*24))

df.insert( 0, 'day', df['days'].apply(get_custom_str_time) )