CODEWITHSUNDEEP
pythonpython-2.7dictionary
Rekoc
Rekoc

Reputation: 438

Delete object save in a dict definitely but keep the key

What I am trying to do is simple, I have a huge dict like so:

class a():
    m=0
    def __init__(self, m):
        self.m = m

    def __int__(self):
        return self.m

b=a(4)
c=a(6523)
d=a(741)
e=a(84521111) 

dict={0:b,1:c,2:e,3:d,4:None,5:None,6:None}

for ele in dict.values():
    if ele is not None:
        print int(ele)
    else:
        print "None"

The real one has 4096 elements. Basically, when I decided to kill the object c, I do:

dict[1]=None

Because I don't want to remove the key number 1, and it is working fine, but the object if still alive somewhere and with 4096 objects it can be a problem on my small embedded system. I can check the alive objects with:

import gc
for obj in gc.get_objects():
    if isinstance(obj, a):
        print obj

Output:

<main.a instance at 0xb749c96c> <main.a instance at 0xb749caac> <main.a instance at 0xb749c9cc> <main.a instance at 0xb749cc0c>

So, how can I delete these object definitely from my memory ?

Nota: del dict[1] doesn't work because it is removed the key as well, same for pop().

I am using Python 2.7, still ...

Upvotes: 0

Views: 92

Answers (1)

Ron Wellman
Ron Wellman

Reputation: 545

Ensure you're accounting for the fact that they were in memory before you added them to the dictionary.

>>> b=a(4)
>>> c=a(6523)
>>> d=a(741)
>>> e=a(84521111) 
>>> 
>>> dict={0:b,1:c,2:e,3:d,4:None,5:None,6:None}
>>> 
>>> for obj in gc.get_objects():
...     if isinstance(obj, a):
...             print obj
... 
<__main__.a instance at 0x7f4078a34dd0>
<__main__.a instance at 0x7f4078a34d88>
<__main__.a instance at 0x7f4078a34d40>
<__main__.a instance at 0x7f4078a34cf8>

Now delete the originals:

>>> del(b)
>>> del(c)
>>> del(d)
>>> del(e)
>>> 
>>> for obj in gc.get_objects():
...     if isinstance(obj, a):
...             print obj
... 
<__main__.a instance at 0x7f4078a34dd0>
<__main__.a instance at 0x7f4078a34d88>
<__main__.a instance at 0x7f4078a34d40>
<__main__.a instance at 0x7f4078a34cf8>

They're still in memory because they're in the dictionary. Now remove them from the dictionary:

>>> dict[3] = None
>>> dict[2] = None
>>> 
>>> for obj in gc.get_objects():
...     if isinstance(obj, a):
...             print obj
... 
<__main__.a instance at 0x7f4078a34dd0>
<__main__.a instance at 0x7f4078a34d88>
>>>

We just lost 2 objects with our delete.

Upvotes: 2

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