Python one-liner of the day

This is a function that takes an integer and returns its ordinal representation, e.g. “1st” for 1 and so on.

It’s not the most readable thing, but once I saw the pieces falling into place I couldn’t help myself. Repetition of the “th” literal is the only thing that bugs me. Oh well.

ord_text = lambda n: "%d%s" % (n, "th" if 10 < n % 100 < 14 else {1:"st", 2:"nd", 3:"rd"}.get(n % 10, "th"))

Comes with a one-line test suite!

for t in "1st 2nd 3rd 4th 11th 12th 13th 21st 22nd 23rd 111th 112th 113th".split(): assert(ord_text(int(t[:-2])) == t)

Matt Tarbit commented :

I think you might need to add 111th, 112th and 113th to the string in your test suite.

(Can’t be certain though because I get a SyntaxError when trying to run your one-liner in python 2.3.4)

Paul commented :

Excelllent catch, Matt, thanks! Fixed.

And yes, I should have mentioned that this is Python 2.5+ only, due to the ternary logic.

Reggie Drake commented :

Unfortunately, your one-liner is so desirous to be a one-liner that on my resolution it reaches way out of the central column of your layout and past the ‘Atom feed’ link.

Leo Petr commented :

Great! Now add internationalization for Russian, Swahili, and Chinese.

Paul commented :

I knew that was coming.

I’ll need a couple more lines.

kbob commented :

Here’s a version that eliminates the repeated “th” AND runs in both Python 2.3 and 2.5.

ord_text = lambda n: str(n) + {1: ‘st’, 2: ’nd’, 3: ‘rd’}.get(n % (10 < n % 100 < 14 or 10), ’th’)

Jason Davies commented :

Nice.

Banibrata Dutta commented :

Hi,

Excellent blogroll/site there. Infact I was happy to find this site running on Django. However, the CSS (I believe, since I’m not too good with web-technologies), may need some mending, because using Google Chrome (or even IE), in a 800px wide window the code-snippets run outside the central pane boundary, and onto the right pane, rendering the text undreadable. Hope that you fix it.

cheers, Banibrata

Paul commented :

Banibrata, thanks for the note. Keep in mind that the lines above are extra-wide by design – they’re supposed to look too long for their own good. Though a style makeover of the site is inevitable, this post won’t be driving it!