[Tutor] Skipping elements from inside generator loops

[Scot W. Stevenson]

Hello Gregor, 

>  >>> zip([None]+p,p)
> [(None, 'black cat'), ('black cat', 'white cat'), ('white cat', 'grey
> cat'),
> ('grey cat', 'ALARM!'), ('ALARM!', 'the evil dog'), ('the evil dog',
> 'fat cat'),
>  ('fat cat', 'slow cat')]

> the second Element of each pair is good if only 'ALARM!' does not occur

> in the pair:
>  >>> [pair[1] for pair in zip([None]+p,p) if 'ALARM!' not in pair]

> ['black cat', 'white cat', 'grey cat', 'fat cat', 'slow cat']
> Not very elegant! Amendments?

This is /sehr beeindruckend/ - and it even works if 'ALARM!' ist the first 
entry. I really like the idea of shifting the first part of the zip call 
with one "None" to produce pairs; this is not something I would have 
thought of...

Thank you for the demonstration, I'll have to go play around with it for a 
while =8).

Y, Scot

-- 
  Scot W. Stevenson -- scot@possum.in-berlin.de -- Zepernick, Germany