else condition in list comprehension

[Anthony]

On Mon, 10 Jan 2005 09:13:17 -0700, Steven Bethard
<steven.bethard at gmail.com> wrote:
> Luis M. Gonzalez wrote:
> > It's me wrote:
> >>> z = [i + (2, -2)[i % 2] for i in range(10)]
> >>
> >> But then why would you want to use such feature?  Wouldn't that make
> >> the code much harder to understand ...
> >> Or are we trying to write a book on "Puzzles in Python"?
> >
> > Once you get used to list comprehensions (and it doesn't take long),
> > they are a more concise and compact way to express these operations.
> 
> After looking the two suggestions over a couple of times, I'm still
> undecided as to which one is more readable for me.  The problem is not
> the list comprehensions (which I love and use extensively).  The problem
> is the odd syntax that has to be used for an if/then/else expression in
> Python.

They're both pretty unreadable, IMHO. Why not just factor out the
if/then/else function like this:

.def plusMinusTwo(i):
.   if  i%2 == 0:
.       return i-2
.   else:
.       return i+2
.
.z = [plusMinusTwo(i) for i in range(10)]

Then you can add whatever you like into the function.

Anthony

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