On 12/14/09 2:24 AM, knifenomad wrote:
On 12월14일, 오전10시19분, knifenomad<knifeno...@gmail.com> wrote:
On 12월14일, 오전2시57분, mattia<ger...@gmail.com> wrote:
Il Sun, 13 Dec 2009 16:37:20 +0000, mattia ha scritto:
How can I insert non-duplicate data in a list? I mean, is there a
particular option in the creation of a list that permit me not to use
something like:
def append_unique(l, val):
if val not in l:
l.append(val)
Thanks,
Mattia
Ok, so you all suggest to use a set. Now the second question, more
interesting. Why can't I insert a list into a set? I mean, I have a
function that returns a list. I call this function several times and
maybe the list returned is the same as another one already returned. I
usually put all this lists into another list. How can I assure that my
list contains only unique lists? Using set does'n work (i.e. the python
interpreter tells me: TypeError: unhashable type: 'list')...
this makes the set type hashable.
class Set(set):
__hash__ = lambda self: id(self)
s = Set()
s.add(1)
s.add(2)
s.add(1)
print s
set([1, 2])
d = {}
d[s] = 'voila'
print d
{Set([1,2]):'voila'}
print d[s]
'voila'- 원본 텍스트 숨기기 -
- 원본 텍스트 보기 -
although it's not what you've asked about. it's intereting to make set
hashable using __hash__.
Thoughtless messing with __hash__ is seldom useful.
>>> s1 = Set([1])
>>> s2 = Set([1])
>>> s1 == s2
True
>>> d = {}
>>> d[s1] = 3
>>> d[s2] = 5
>>> d
{Set([1]): 3, Set([1]): 5}
>>>
Equality is kept for comparison, but what is it worth to hash
them by id?
On the original problem:
You could turn you lists into tuples. This would be clean
and correct.
ciao - chris
--
Christian Tismer :^)<mailto:tis...@stackless.com>
tismerysoft GmbH : Have a break! Take a ride on Python's
Johannes-Niemeyer-Weg 9A : *Starship* http://starship.python.net/
14109 Berlin : PGP key -> http://wwwkeys.pgp.net/
work +49 30 802 86 56 mobile +49 173 24 18 776 fax +49 30 80 90 57 05
PGP 0x57F3BF04 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04
whom do you want to sponsor today? http://www.stackless.com/
--
http://mail.python.org/mailman/listinfo/python-list
