CODEWITHSUNDEEP
pythonnumpymemory-leaksgarbage-collectionnumpy-ndarray
Nic
Nic

Reputation: 677

Numpy: garbage collection after slicing

def foo():
    x = np.ones((10,10))
    return x[:5,:5]

If I call y = foo() I'll get a 5x5 array (1/4 of the values in x). But what happens to the other values in x, do they persist in memory or get garbage collected in some way? I'd like to understand this.

Upvotes: 5

Views: 850

Answers (1)

user2357112
user2357112

Reputation: 280426

As kindall says in the comments, basic slicing on a NumPy array creates a view of the original array. The view has to keep the entire original object alive; you can see the reference it uses to do so in the view's base attribute.

In [2]: x = numpy.ones((10, 10))

In [3]: y = x[:5, :5]

In [4]: y.base is x
Out[4]: True

Upvotes: 3

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