Difference between list(numpy_array) and numpy_array.tolist()

Question

What is the difference between applying list() on a numpy array vs. calling tolist()?

I was checking the types of both output

Answer 1

The major difference is that tolist recursively converts all data to python standard library types.

For instance:

>>> arr = numpy.arange(2)
>>> [type(item) for item in list(arr)]
[numpy.int64, numpy.int64]
>>> [type(item) for item in arr.tolist()]
[builtins.int, builtins.int]

Aside from the functional differences tolist will generally be quicker as it knows it has a numpy array and access to the backing array. Whereas, list will fall back to using an iterator to add all the elements.

In [2]: arr = numpy.arange(1000)

In [3]: %timeit arr.tolist()
10000 loops, best of 3: 33 µs per loop

In [4]: %timeit list(arr)
10000 loops, best of 3: 80.7 µs per loop

I would expect the tolist to be