testing array of logicals

[John Henry]

Hi list,

Is there a more elagant way of doing this?

# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

--
Thanks,

[Stefan Behnel]

Re: testing array of logicals

John Henry wrote:

Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

Py2.5:

test = all( logflags )

Py2.4 (although somewhat ugly):

try:
test = itertools.ifilt erfalse( logflags ).next()
except StopIteration:
test = True

otherwise: your above code will do just fine. Note that you can shortcut,
though, if any of the flags evaluates to False:

test = True
for x in logflags:
if not x:
test = False
break

Stefan

[Fredrik Lundh]

Re: testing array of logicals

John Henry wrote:

Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

your code checks all members, even if the first one's false. that's not
very elegant. here's a better way to do it:

def all(S):
for x in S:
if not x:
return False
return True

print all(logfiles)

if you upgrade to 2.5, you can get rid of the function definition; "all"
is a built-in in 2.5.

also see:

http://www.artima.com/weblogs/viewpost.jsp?thread=98196

</F>

[Ant]

Re: testing array of logicals


John Henry wrote:

Hi list,
>
Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

There's reduce, but it's not as explicit, and see F's post RE
efficiency:

>>x = [True, True, True]
>>y = [True, False, True]
>>print reduce(lambda a, b: a and b, x)

True

>>print reduce(lambda a, b: a and b, y)

False

>>>

[Gary Herron]

Re: testing array of logicals

John Henry wrote:

Hi list,
>
Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test
>
--
Thanks,
>
>

The builtin "reduce" does that kind of thing for any function you wish
to apply across the list. So then its only a matter of giving it a
function that "and"s two arguments:

Either:
reduce(lambda a,b: a and b, logFlags)
or
def and2(a,b):
return a and b

reduce(and2, logFlags)

Gary Herron

[Alex Martelli]

Re: testing array of logicals

John Henry <john106henry@h otmail.comwrote :

Hi list,
>
Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

test = sum(bool(x) for x in logflags)==len( logflags)

is yet another possibility (without the effectiveness of
shortcircuiting , just like the quoted approach). Some might prefer

test = not sum(not x for x in logflags)

but that's starting to border on the obscure;-).

If by "logicals" you mean "bool" instances (True and False) only, then

test = sum(logflags) == len(logflags)

is simpler and fast than, but equivalent to, my first suggestion.


Alex

[Paul Rubin]

Re: testing array of logicals

"John Henry" <john106henry@h otmail.comwrite s:

# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

print (False not in map(bool, logflags))

Possibly more "pure" alternative (untested):

from operator import and_
print reduce(and_, map(bool, logflags))

[Simon Brunning]

Re: testing array of logicals

On 12 Jul 2006 11:14:43 -0700, John Henry <john106henry@h otmail.comwrote :

Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

min(logflags)

I feel dirty now. ;-)

--
Cheers,
Simon B,
simon@brunningo nline.net,

http://www.brunningonline.net/simon/blog/

[John Henry]

Re: testing array of logicals


Simon Brunning wrote:

On 12 Jul 2006 11:14:43 -0700, John Henry <john106henry@h otmail.comwrote :

Is there a more elagant way of doing this?

# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test

>
min(logflags)
>

!!!

I feel dirty now. ;-)
>

ROFL

Thanks to everybody that replied.

--
Cheers,
Simon B,
simon@brunningo nline.net,
http://www.brunningonline.net/simon/blog/

[Simon Brunning]

Re: testing array of logicals

On 13 Jul 2006 05:45:21 -0700, John Henry <john106henry@h otmail.comwrote :

>
Simon Brunning wrote:

min(logflags)

>
!!!

Be aware that not only is this an outrageous misuse of min(), it's
also almost certainly much less efficient than /F's suggestion, 'cos
it always iterates through the entire list.

--
Cheers,
Simon B,
simon@brunningo nline.net,

http://www.brunningonline.net/simon/blog/

[Bruno Desthuilliers]

Re: testing array of logicals

Simon Brunning a écrit :

On 13 Jul 2006 05:45:21 -0700, John Henry <john106henry@h otmail.comwrote :
>

>>
>Simon Brunning wrote:

>
min(logflags)
>

>>
>!!!

>
>
Be aware that not only is this an outrageous misuse of min(),

+1 QOTW

Ho, my, I've already proposed another one today :(

[Simon Forman]

Re: testing array of logicals


John Henry wrote:

Hi list,
>
Is there a more elagant way of doing this?
>
# logflags is an array of logicals
test=True
for x in logflags:
test = test and x
print test
>
--
Thanks,

So many ways.... *drool*
How about:

False not in logflags


(Anybody gonna run all these through timeit? ;P )

[Simon Forman]

Re: testing array of logicals

>

False not in logflags
>

Or, if your values aren't already bools

False not in (bool(n) for n in logflags)



Peace,
~Simon

[John Henry]

Re: testing array of logicals


Simon Forman wrote:

False not in logflags

>
Or, if your values aren't already bools
>
False not in (bool(n) for n in logflags)
>
>
>
Peace,
~Simon

Very intriguing use of "not in"...

Thanks,

[Janto Dreijer]

Re: testing array of logicals

John Henry wrote:

Simon Forman wrote:

>
False not in logflags
>

Or, if your values aren't already bools

False not in (bool(n) for n in logflags)

>
Very intriguing use of "not in"...

Is there a reason why you didn't write
True in (bool(n) for n in logflags)