conditional expression sought

[Elaine Jackson]

This is a good idea. Thanks for pointing it out.

"Dave K" <dk123456789 at REMOVEhotmail.com> wrote in message
news:866j101bbuuhtpan29eop9o4mk1mt7nckn at 4ax.com...
| On Thu, 29 Jan 2004 17:58:45 GMT in comp.lang.python, "Elaine Jackson"
| <elainejackson7355 at home.com> wrote:
|
| >If bool(B_i)==True for 1<=i<=n and j is the smallest i with bool(A_j)==True,
| >then the evaluation of (A_1 and B_1) or ... or (A_n and B_n) returns B_j
without
| >evaluating any other B_i. This is such a useful mode of expression that I
would
| >like to be able to use something similar even when there is an i with
| >bool(B_i)==False. The only thing I can think of by myself is ( (A_1 and
[B_1])
| >or ... or (A_n and [B_n]) )[0], and I can't be satisfied with that for
obvious
| >reasons. Does anybody know a good way to express this? Any help will be mucho
| >appreciado.
| >
| >Peace
| >
|
| I'm not sure if this is what you're looking for, but for i > a very
| small number, the zip function seems more appropriate:
|
| >>> def get_B_i(A, B):
|     for a, b in zip(A, B):
|     if a: return b
|     return A[-1]
| >>> print get_B_i([False, False, True, False], [0, 1, 2, 3])
| 2
| >>> print get_B_i([False, False, False, False], [0, 1, 2, 3])
| False
|
| This has exactly the same effect provided that A and B are the same
| length, otherwise the return value by failure should be adjusted to
| whatever suits your purpose.
|
| If you really want to write a conditional expression out in full, I
| can't think of anything non-clumsy that would work for all possible
| values of B_i, so unfortunately can't help you there.
|
| Dave
|
|