Following up to David Morrissey's answer on 'How to clone a list in python?' I was running some performance tests and hit unexpected behavior when working w/ numpy arrays. I know that a numpy array can/ should be cloned w/
clone = numpy.array(original)
or
clone = numpy.copy(original)
but have incorrectly assumed that slicing would do the trick too. However:
In [11]: original = numpy.arange(4)
In [12]: original
Out[12]: array([0, 1, 2, 3])
In [13]: clone = original[:]
In [14]: clone
Out[14]: array([0, 1, 2, 3])
In [15]: clone[0] = 1
In [16]: clone
Out[16]:开发者_JAVA技巧 array([1, 1, 2, 3])
In [17]: original
Out[17]: array([1, 1, 2, 3])
Is there a good reason for this slight inconsistency or should I file a bug?
In numpy, slices are references or "views" on the original array, so they are not copies. That is by design, not a bug. The reason is that a copy is not as useful as a view.
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