Python: Date Ordinal Output?

Question

I'm wondering if there is a quick and easy way to output ordinals given a number in python.

For example, given the number 1, I'd like to output "1st", the number 2, "2nd", et cetera, et cetera.

This is for working with dates in a breadcrumb trail

Home >  Venues >  Bar Academy >  2009 >  April >  01

is what is currently shown

I'd like to have something along the lines of

Home >  Venues >  Bar Academy >  2009 >  April >  1st

Answer 1

Except for 1st, 2nd, and 3rd, I think they all just add th... 4th, 5th, 6th, 11th, 21st ... oh, oops ;-)

I think this might work:

def ordinal(num):
     ldig = num % 10
     l2dig = ldig % 10
     if l2dig == 1:
         suffix = 'th'
     elif ldig == 1:
         suffix = 'st'
     elif ldig == 2:
         suffix = 'nd'
     elif ldig == 3:
         suffix = 'rd'
     else: 
         suffix = 'th'
     return '%d%s' % (num, suffix)

Answer 2

Or shorten David's answer with:

if 4 <= day <= 20 or 24 <= day <= 30:
    suffix = "th"
else:
    suffix = ["st", "nd", "rd"][day % 10 - 1]

Attribution.

Answer 3

Here's a more general solution:

def ordinal(n):
    if 10 <= n % 100 < 20:
        return str(n) + 'th'
    else:
       return  str(n) + {1 : 'st', 2 : 'nd', 3 : 'rd'}.get(n % 10, "th")

Answer 4

Here it is using dictionaries as either a function or as a lambda...

If you look at the dictionaries backwards you can read it as...

Everything ends in 'th'

...unless it ends in 1, 2, or 3 then it ends in 'st', 'nd', or 'rd'

...unless it ends in 11, 12, or 13 then it ends in 'th, 'th', or 'th'

# as a function
def ordinal(num):
    return '%d%s' % (num, { 11: 'th', 12: 'th', 13: 'th' }.get(num % 100, { 1: 'st',2: 'nd',3: 'rd',}.get(num % 10, 'th')))

# as a lambda
ordinal = lambda num : '%d%s' % (num, { 11: 'th', 12: 'th', 13: 'th' }.get(num % 100, { 1: 'st',2: 'nd',3: 'rd',}.get(num % 10, 'th')))

Answer 5

Here is an even shorter general solution:

def foo(n):
    return str(n) + {1: 'st', 2: 'nd', 3: 'rd'}.get(4 if 10 <= n % 100 < 20 else n % 10, "th")

Although the other solutions above are probably easier to understand at first glance, this works just as well while using a bit less code.