MemoryError when list append... plz help

Gabriel Genellina gagsl-py2 at
Wed Dec 31 19:57:03 CET 2008

En Wed, 31 Dec 2008 06:34:48 -0200, Steven D'Aprano  
<steve at> escribió:

> Each time you are appending to the list, you append a tuple:
> ((i, j), sim)
> where sim is a float and i and j are ints. How much memory does each of
> those take?
>>>> sys.getsizeof( ((0, 1), 1.1) )
> 32

(On Windows, 32 bits, I get 36)

> So each entry requires 32 bytes. 60 million times 32 bytes = almost 2GB
> alone. Plus the list itself will require (approximately) between 230MB
> and 460MB just for the pointers.

That was just the size of the "outer" tuple; you have to add the size of  
each element too. First one is another 2-item tuple (36 bytes too) plus  
its elements (two integers, 12 bytes each). Second element is a float and  
takes 16 bytes. Total: 112 bytes per item; the final size may be a bit  
smaller because some objects may be shared (e.g. small integers)

Gabriel Genellina

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