Python program to print Calendar without calendar or datetime module

Given the month and year. The task is to show the calendar of that month and in the given year without using any module or pre-defined functions.

Examples:

Input : 
mm(1-12) :9
yy :2010

Output :    
September 2010
Su Mo Tu We Th Fr Sa
         01 02 03 04 
05 06 07 08 09 10 11 
12 13 14 15 16 17 18 
19 20 21 22 23 24 25 
26 27 28 29 30 

Approach:

In the program below, we first calculate the number of odd days to find the day of the date 01-mm-yyyy.Then, we take in the year(yy) and the month(mm) as input and displays the calendar for that month of the year.

Below is the implementation of the given approach.

# Python code to print Calendar
# Without use of Calendar module

mm = 2
yy = 2020

month ={1:'January', 2:'February', 3:'March',
        4:'April', 5:'May', 6:'June', 7:'July',
        8:'August', 9:'September', 10:'October',
        11:'November', 12:'December'}

# code below for calculation of odd days
day =(yy-1)% 400
day = (day//100)*5 + ((day % 100) - (day % 100)//4) + ((day % 100)//4)*2
day = day % 7

nly =[31, 28, 31, 30, 31, 30,
      31, 31, 30, 31, 30, 31]
ly =[31, 29, 31, 30, 31, 30,
     31, 31, 30, 31, 30, 31]
s = 0

if yy % 4 == 0:
    for i in range(mm-1):
        s+= ly[i]
else:
    for i in range(mm-1):
        s+= nly[i]

day += s % 7
day = day % 7

# variable used for white space filling
# where date not present
space =''
space = space.rjust(2, ' ')

# code below is to print the calendar
print(month[mm], yy)
print('Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa')

if mm == 9 or mm == 4 or mm == 6 or mm == 11:
    for i in range(31 + day):

        if i<= day:
            print(space, end =' ')
        else:
            print("{:02d}".format(i-day), end =' ')
            if (i + 1)% 7 == 0:
                print()
elif mm == 2:
    if yy % 4 == 0:
        p = 30
    else:
        p = 29

    for i in range(p + day):
        if i<= day:
            print(space, end =' ')
        else:
            print("{:02d}".format(i-day), end =' ')
            if (i + 1)% 7 == 0:
                print()
else:
    for i in range(32 + day):

        if i<= day:
            print(space, end =' ')
        else:
            print("{:02d}".format(i-day), end =' ')
            if (i + 1)% 7 == 0:
                print()

Output:

February 2020
Su Mo Tu We Th Fr Sa
                  01 
02 03 04 05 06 07 08 
09 10 11 12 13 14 15 
16 17 18 19 20 21 22 
23 24 25 26 27 28 29