On Fri, 25 Mar 2005 12:07:23 -0800, Michael Spencer <[EMAIL PROTECTED]> wrote:
>Scott David Daniels wrote:
>> Michael Spencer wrote:
>>
>>> itertools.groupby enables you to do this, you just need to define a
>>> suitable grouping function, that stores its state:
>>
>>
>> Michael, this would make a great Python Cookbook Recipe.
>>
>OK, will do. What would you call it? Something like: "Stateful grouping of
>iterable items"
>
>[Bengt]:
>> Nice, but I think "record" is a bit opaque semantically.
>> How about group_id or
>> generate_incrementing_unique_id_for_each_group_to_group_by or such?
>>
>> Regards,
>> Bengt Richter
>
>Agreed, it's an issue. I think the most natural name is groupby - but that
>would cause more trouble. What do you think about 'grouping' ?
>I would use 'generate_incrementing_unique_id_for_each_group_to_group_by', but
>then people might think I'm trying to outdo Bob Ippolito :-)
>
>[Serge]:
>> I think your example would
>> be more clear for Jordan if you used function attributes:
>>
>> def record(item):
>> if len(item) > 20:
>> record.seq +=1
>> return record.seq
>> record.seq = 0
>
>That does read better than the mutable default argument hack. Is this use of
>function attributes generally encouraged? (I tend to think of func_dict for
>meta-data, used only outside the function) Thoughts?
>
Personally, I don't like depending on an externally bound (and rebindable)
(usually global)
name as a substitute for "self." You could always use a class to carry state,
e.g. (untested)
class Grouper(object):
def __init__(self): self.group_id = 0
def __call__(self, item):
if len(item) > 20: self.group_id += 1 # advance id to next group
return self.group_id
# ...
grouper = Grouper()
# ...
for groupnum, lines in groupby(linesource, grouper):
print "".join(lines)
Or (guess I better actually try this one ;-)
>>> linesource = """\
... Here is a long line, long line, long line
... and this is short
... and this is short
... Here is a long line, long line, long line
... and this is short""".splitlines()
>>>
>>> for groupnum, lines in groupby(linesource, type('',(),{'n':0,
>>> '__call__':lambda s,i: setattr(s,'n', s.n+(i>20)) or s.n})()):
... print "".join(lines)
...
Here is a long line, long line, long line
and this is short
and this is short
Here is a long line, long line, long line
and this is short
Regards,
Bengt Richter
--
http://mail.python.org/mailman/listinfo/python-list
