In-memory size of python stucture

Question

Does someone know of a good reference card for the memory size of python data stucture on 32 and 64 bit platforms ?

If not, this would be nice to have it on SO. The more exhaustive the better ! So how many bytes are used by those python structures (depending on the len and the content type when relevant) ?

 - int
 - float
 - reference
 - str
 - unicode string
 - tuple
 - list
 - dict
 - set
 - array.array
 - numpy.array
 - deque
 - new-style classes object
 - old-style classes object
 - ... and everything I am forgetting !

(for containers that keep only references to other objects, we obviously do not want to count the size of the item themselves, since they may be shared)

Furthermore, is there a way to get the memory used by an object at runtime (recursively or not) ?

Answer 1

The recommendation from an earlier question on this was to use sys.getsizeof(), quoting:

>>> import sys
>>> x = 2
>>> sys.getsizeof(x)
14
>>> sys.getsizeof(sys.getsizeof)
32
>>> sys.getsizeof('this')
38
>>> sys.getsizeof('this also')
48

You could take this approach:

>>> import sys
>>> import decimal
>>> d = {}
>>> d["int"] = 1
>>> d["float"] = 2.9
>>> d["dict"] = dict()
>>> d["set"] = set()
>>> d["tuple"] = tuple()
>>> d["list"] = list()
>>> d["str"] = "a"
>>> d["unicode"] = u"a"
>>> d["decimal"] = decimal.Decimal(0)
>>> d["object"] = object()
>>> for k in sorted(d):
...     print k, sys.getsizeof(d[k])
...
decimal 40
dict 140
float 16
int 12
list 36
object 8
set 116
str 25
tuple 28
unicode 28

Answer 2

I've been happily using pympler for such tasks. It's compatible with many versions of Python -- the asizeof module in particular goes back to 2.2!

For example, using hughdbrown's example but with from pympler import asizeof at the start and print asizeof.asizeof(v) at the end, I see (system Python 2.5 on MacOSX 10.5):

$ python pymp.py 
set 120
unicode 32
tuple 32
int 16
decimal 152
float 16
list 40
object 0
dict 144
str 32

Clearly there is some approximation here, but I've found it very useful for footprint analysis and tuning.