[Tutor] Else in list comprehension

[jfouhy@paradise.net.nz]

Quoting Max Noel <maxnoel_fr at yahoo.fr>:

>  Apparently, no. I just tried:
> 
>  >>> b = [i for i in range(10) if (i % 2) == 0 else 0]

You can sometimes do a bit of trickery with and/or.  eg:

>>> odds = [(i % 2 == 1 and i or -1) for i in range(10)]
>>> odds
[-1, 1, -1, 3, -1, 5, -1, 7, -1, 9]

The big gotcha here is if any of the data you are interested in could be 0.  You
can progress to further trickery, but the payoff isn't always worth it.

Sometimes you just have to write a loop :-)

-- 
John.