On Thu, Dec 3, 2015 at 8:27 PM, <[email protected]> wrote:
> Thank you for your suggestion. This will help a lot.
>
> On 2015-12-03 08:32 Jussi Piitulainen <[email protected]> wrote:
>> list = [ item for item in list
>> if ( 'Banana' not in item and
>> 'Car' not in item ) ]
>
> I often saw constructions like this
> x for x in y if ...
> But I don't understand that combination of the Python keywords (for,
> in, if) I allready know. It is to complex to imagine what there really
> happen.
>
> I understand this
> for x in y:
> if ...
>
> But what is about the 'x' in front of all that?
It's called a *list comprehension*. The code Jussi posted is broadly
equivalent to this:
list = []
for item in list:
if ( 'Banana' not in item and
'Car' not in item ):
list.append(item)
I recently came across this blog post, which visualizes comprehensions
fairly well.
http://treyhunner.com/2015/12/python-list-comprehensions-now-in-color/
The bit at the beginning (before the first 'for') goes inside a
list.append(...) call, and then everything else is basically the same.
ChrisA
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