In [1]:

    

import calendar
import datetime


    

In [2]:

    

def get_day_of_last_week(year, month, dow):
    '''dow: Monday(0) - Sunday(6)'''
    n = calendar.monthrange(year, month)[1]
    l = range(n - 6, n + 1)
    w = calendar.weekday(year, month, l[0])
    w_l = [i % 7 for i in range(w, w + 7)]
    return l[w_l.index(dow)]


    

In [3]:

    

print(calendar.month(2019, 1))


    

    




    January 2019
Mo Tu We Th Fr Sa Su
    1  2  3  4  5  6
 7  8  9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31

In [4]:

    

print(get_day_of_last_week(2019, 1, 0))


    

    




28

In [5]:

    

print(get_day_of_last_week(2019, 1, 3))


    

    




31

In [6]:

    

print(get_day_of_last_week(2019, 1, 4))


    

    




25

In [7]:

    

year = 2019
month = 1
dow = 0


    

In [8]:

    

n = calendar.monthrange(year, month)[1]
print(n)


    

    




31

In [9]:

    

l = range(n - 6, n + 1)
print(list(l))


    

    




[25, 26, 27, 28, 29, 30, 31]

In [10]:

    

w = calendar.weekday(year, month, l[0])
print(w)


    

    




4

In [11]:

    

w_l = [i % 7 for i in range(w, w + 7)]
print(w_l)


    

    




[4, 5, 6, 0, 1, 2, 3]

In [12]:

    

print(l[w_l.index(dow)])


    

    




28

In [13]:

    

def get_date_of_last_week(dt, dow):
    '''dow: Monday(0) - Sunday(6)'''
    return dt.replace(day=get_day_of_last_week(dt.year, dt.month, dow))


    

In [14]:

    

dt = datetime.datetime(2019, 1, 10, 10, 10, 10)
print(dt)


    

    




2019-01-10 10:10:10

In [15]:

    

print(get_date_of_last_week(dt, 0))


    

    




2019-01-28 10:10:10

In [16]:

    

print(get_date_of_last_week(dt, 3))


    

    




2019-01-31 10:10:10

In [17]:

    

d = datetime.date(2019, 1, 10)
print(d)


    

    




2019-01-10

In [18]:

    

print(get_date_of_last_week(d, 0))


    

    




2019-01-28

In [19]:

    

print(get_date_of_last_week(d, 3))


    

    




2019-01-31

In [20]:

    

def get_date_of_last_week2(year, month, dow):
    '''dow: Monday(0) - Sunday(6)'''
    return datetime.date(year, month, get_day_of_last_week(year, month, dow))


    

In [21]:

    

print(get_date_of_last_week2(2019, 1, 0))


    

    




2019-01-28