On Friday 01 July 2005 12:35 am, David Pratt wrote:
> Wow Robert that is incredible python magic! I am trying to figure out
> what this is doing since my attempts were regex and some long string
> splitting and collection.
Try it out in the interpreter:
Test data:
>>> test = "'en' | 'the brown cow' | 'fr' | 'la vache brun'"
Splitting, you already know:
>>> line.split('|')
["'en' ", " 'the brown cow' ", " 'fr' ", " 'la vache brun'"]
The list comprehension generates a new list based on the old one,
in this case, using the string method strip to remove spaces and
single quotes:
>>> translations = [x.strip(" '") for x in line.split('|')]
>>> translations
['en', 'the brown cow', 'fr', 'la vache brun']
Then Robert did some real magic by using extended slice notation:
>>> translations[::2]
['en', 'fr']
(count from 0, every 2nd element)
>>> translations[1::2]
['the brown cow', 'la vache brun']
(count from 1, every 2nd element)
This, of course, is to generate two parallel lists from your one.
"zip" well, *zips* two or more lists together:
>>> zip(translations[::2], translations[1::2])
[('en', 'the brown cow'), ('fr', 'la vache brun')]
Which is all ready for the dict constructor:
>>> dict(zip(translations[::2], translations[1::2]))
{'fr': 'la vache brun', 'en': 'the brown cow'}
I always find it helps to take a statement apart in the interpreter if
a little too much is going on in one line for me to follow.
--
Terry Hancock ( hancock at anansispaceworks.com )
Anansi Spaceworks http://www.anansispaceworks.com
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