Better way to negate a boolean list?

[David Trémouilles]

Hi,

Is there any better (shorter) way to negate a boolean list than:

>>> negated_boolean_list = [not elem for elem in boolean_list]

?

I tried:but it seems that "not" is not a function.

Thanks in advance,

David

 

[Paddy]

Hi,

Is there any better (shorter) way to negate a boolean list than:

negated_boolean_list = [not elem for elem in boolean_list]

?

I tried:but it seems that "not" is not a function.

Thanks in advance,

David

Try [not x for x in boolean_list]

- Paddy.

 

[Steve Holden]

Hi,

Is there any better (shorter) way to negate a boolean list than:

negated_boolean_list = [not elem for elem in boolean_list]

?

I tried:

map(not, boolean_list)

but it seems that "not" is not a function.

Thanks in advance,

David

Try [not x for x in boolean_list]

This six-character shortening by renaming the comprehension's bound
variable was a joke, right?

regards
Steve

 

[Stargaming]

but it seems that "not" is not a function.[/QUOTE]

`not` is not a function, indeed. It is a keyword, allowing you to write
``not x`` instead of ``not(x)``.

You can of course write a function that just returns its input negated
and pass this function to `map`. Since Python comes with batteries
included, there is such a function already in the `operator module
<http://docs.python.org/lib/module-operator.html>`_::

import operator
map(operator.not_, boolean_list)
# ^ underscore to distinguish from the keyword

Cheers,

 

[Paddy]

Hi,
Is there any better (shorter) way to negate a boolean list than:
negated_boolean_list = [not elem for elem in boolean_list]
?
I tried:
map(not, boolean_list)
but it seems that "not" is not a function.
Thanks in advance,
David

Try [not x for x in boolean_list]

This six-character shortening by renaming the comprehension's bound
variable was a joke, right?

No,
Of course not!
It's much worse - I completely missed the line beginning negated_....
on
first and second reading.
I am indeed getting older, although I had thought I was way off my
dotage.

- Paddy.