如何知道python对象的字节大小,如数组和字典? - 简单的方法

问题描述 投票:38回答:4

我正在寻找一种简单的方法来了解数组和字典对象的字节大小,比如

[ [1,2,3], [4,5,6] ] or { 1:{2:2} }

很多主题都说使用pylab,例如:

from pylab import *

A = array( [ [1,2,3], [4,5,6] ] )
A.nbytes
24

但是,字典怎么样?我看到很多答案建议使用pysize或heapy。 Torsten Marek在这个链接中给出了一个简单的答案:Which Python memory profiler is recommended?,但我对输出没有明确的解释,因为字节数不匹配。

Pysize似乎更复杂,我还没有明确如何使用它。

鉴于我想要执行的大小计算的简单性(没有类或复杂的结构),任何关于如何简单估计这种对象的内存使用量的想法?

亲切的问候。

python object memory size byte
4个回答
48
投票

有:

>>> import sys
>>> sys.getsizeof([1,2, 3])
96
>>> a = []
>>> sys.getsizeof(a)
72
>>> a = [1]
>>> sys.getsizeof(a)
80

但我不会说它是可靠的,因为Python对每个对象都有开销,并且有些对象除了引用其他对象之外什么也没有,所以它与C和其他语言不完全相同。

阅读有关sys.getsizeof的文档并从那里开始我想。


27
投票

派对有点晚,但是获得dict大小的简单方法就是首先腌制它。

在python对象(包括字典)上使用sys.getsizeof可能不准确,因为它不计算引用的对象。

处理它的方法是将其序列化为字符串并在字符串上使用sys.getsizeof。结果将更接近您想要的结果。

import cPickle

mydict = {'key1':'some long string, 'key2':[some, list], 'key3': whatever other data}

做sys.getsizeof(mydict)并不是那么精确,先腌渍它

mydict_as_string = cPickle.dumps(mydict)

现在我们可以知道它需要多少空间

print sys.getsizeof(mydict_as_string)

16
投票

这里的答案都不是真正的通用。

以下解决方案将以递归方式处理任何类型的对象,而无需昂贵的递归实现:

import gc
import sys

def get_obj_size(obj):
    marked = {id(obj)}
    obj_q = [obj]
    sz = 0

    while obj_q:
        sz += sum(map(sys.getsizeof, obj_q))

        # Lookup all the object referred to by the object in obj_q.
        # See: https://docs.python.org/3.7/library/gc.html#gc.get_referents
        all_refr = ((id(o), o) for o in gc.get_referents(*obj_q))

        # Filter object that are already marked.
        # Using dict notation will prevent repeated objects.
        new_refr = {o_id: o for o_id, o in all_refr if o_id not in marked and not isinstance(o, type)}

        # The new obj_q will be the ones that were not marked,
        # and we will update marked with their ids so we will
        # not traverse them again.
        obj_q = new_refr.values()
        marked.update(new_refr.keys())

    return sz

例如:

>>> import numpy as np
>>> x = np.random.rand(1024).astype(np.float64)
>>> y = np.random.rand(1024).astype(np.float64)
>>> a = {'x': x, 'y': y}
>>> get_obj_size(a)
16816

有关更多信息,请参阅my repository,或者只需安装我的软件包(objsize):

$ pip install objsize

然后:

>>> from objsize import get_deep_size
>>> get_deep_size(a)
16816

12
投票

使用此配方,取自此处:

http://code.activestate.com/recipes/577504-compute-memory-footprint-of-an-object-and-its-cont/

from __future__ import print_function
from sys import getsizeof, stderr
from itertools import chain
from collections import deque
try:
    from reprlib import repr
except ImportError:
    pass

def total_size(o, handlers={}, verbose=False):
    """ Returns the approximate memory footprint an object and all of its contents.

    Automatically finds the contents of the following builtin containers and
    their subclasses:  tuple, list, deque, dict, set and frozenset.
    To search other containers, add handlers to iterate over their contents:

        handlers = {SomeContainerClass: iter,
                    OtherContainerClass: OtherContainerClass.get_elements}

    """
    dict_handler = lambda d: chain.from_iterable(d.items())
    all_handlers = {tuple: iter,
                    list: iter,
                    deque: iter,
                    dict: dict_handler,
                    set: iter,
                    frozenset: iter,
                   }
    all_handlers.update(handlers)     # user handlers take precedence
    seen = set()                      # track which object id's have already been seen
    default_size = getsizeof(0)       # estimate sizeof object without __sizeof__

    def sizeof(o):
        if id(o) in seen:       # do not double count the same object
            return 0
        seen.add(id(o))
        s = getsizeof(o, default_size)

        if verbose:
            print(s, type(o), repr(o), file=stderr)

        for typ, handler in all_handlers.items():
            if isinstance(o, typ):
                s += sum(map(sizeof, handler(o)))
                break
        return s

    return sizeof(o)


##### Example call #####

if __name__ == '__main__':
    d = dict(a=1, b=2, c=3, d=[4,5,6,7], e='a string of chars')
    print(total_size(d, verbose=True))
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