[BangPypers] Reorder Dictionary Size in python

[Rahul R]

Hey Hrishikesk,

So are you saying, if i run gc.collect() in my program I will get rid of
all the dummy variables in the dictionary ?

Thanks,
./Rahul

On Thu, Apr 18, 2013 at 12:06 PM, Hrishikesh Kulkarni
<rishi at turtleyogi.com>wrote:

> On Wed, Apr 17, 2013 at 9:30 PM, Rahul R <rahul8590 at gmail.com> wrote:
>
> > As far as i know, python performs a lazy deletion of values , when we
> > delete content from a dictionary (correct me if i am wrong) .  So, when
> we
> > insert a lot of values the dictionary automatically expands. I don't see
> > dict shrinking when we delete values from dictionary. In such case, is
> > there a way to forcibly reduce the dictionary size ?
> >
>
>
> Are you measuring this shrinking?
> the following  in dictobject.c should guide you with the internals. The
> deleted item is simply replaced with a refcounted dummy. The deleted item
> is marked for cleanup by gc with decref.
>
> PyDict_DelItem () :
> ..
>     old_key = ep->me_key;
>     Py_INCREF(dummy);
>     ep->me_key = dummy;
>     old_value = ep->me_value;
>     ep->me_value = NULL;
>     mp->ma_used--;
>     Py_DECREF(old_value);
>     Py_DECREF(old_key);
> ..
>
>
> dict_length():
> ..
>     return mp->ma_used;
> ..
>
> PyDict_Size():
> ..
>     return ((PyDictObject *)mp)->ma_used;
> ..
>
>
>
> regards,
> Rishi
>
>
>
>
> >
> > ./Rahul
> >
> > On Wed, Apr 17, 2013 at 9:23 PM, Ramdas S <ramdaz at gmail.com> wrote:
> >
> > > On Wed, Apr 17, 2013 at 9:22 PM, Rahul R <rahul8590 at gmail.com> wrote:
> > >
> > > > Ahh , sorry If i wasnt clear the first time. I dint mean reorder the
> > data
> > > > in dictionary. I meant resize the dictionary.
> > > >
> > >
> > > What do you mean by resize?
> > >
> > >
> > > >
> > > > ./Rahul
> > > >
> > > > On Wed, Apr 17, 2013 at 9:05 PM, Anand Chitipothu <
> > anandology at gmail.com
> > > > >wrote:
> > > >
> > > > > dictionaries are unordered. It is not a good idea to expect any
> order
> > > in
> > > > > dictionaries, even if you are seeing some order by chance.
> > > > >
> > > > > If you need order, then use OrderedDict from collections module
> (new
> > in
> > > > > Python 2.7).
> > > > >
> > > > > Anand
> > > > >
> > > > >
> > > > > On Wed, Apr 17, 2013 at 9:00 PM, Rahul R <rahul8590 at gmail.com>
> > wrote:
> > > > >
> > > > > > Hey  Guys,
> > > > > >
> > > > > > Is it possible to forcibly reorder the python dictionary after
> "n"
> > > > number
> > > > > > of inserts and deletions. As far as i know, python dictionary
> > > performs
> > > > > lazy
> > > > > > deletes. Thus , even if the data is deleted, python has a dummy
> > data
> > > > > their
> > > > > > in order to preserve consistency. The python dictionary
> > > > > > keeps expanding when the size of dict is increasing, but after
> > > > deleting a
> > > > > > few parameters the size does not decrease. Is there a way ,
> where I
> > > can
> > > > > > forcibly resize the dictionary ?
> > > > > >
> > > > > > I was thinking of copying content from existing dictionary to new
> > > dict
> > > > > and
> > > > > > deleting the previous one.But thats a cumbersome operation.
> > > > > >
> > > > > > Thanks,
> > > > > > ./Rahul
> > > > > > _______________________________________________
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> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Anand
> > > > > http://anandology.com/
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> > >
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> > >
> > > --
> > > Ramdas S
> > > +91 9342 583 065
> > > My Personal Blog on http://ramdaz.wordpress.com
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