Does numpy reshape create a copy?
For Python keep in mind that several variables or names can point to the same object, such as a numpy array. Arrays can also have views, which are new array objects, but with shared data buffers. A copy has its own data buffer.
In [438]: x = np.arange(12)In [439]: y = x # same objectIn [440]: y.shape = (2,6) # inplace shape changeIn [441]: yOut[441]: array([[ 0, 1, 2, 3, 4, 5], [ 6, 7, 8, 9, 10, 11]])In [442]: xOut[442]: array([[ 0, 1, 2, 3, 4, 5], [ 6, 7, 8, 9, 10, 11]])In [443]: y = y.reshape(3,4) # y is a new viewIn [444]: yOut[444]: array([[ 0, 1, 2, 3], [ 4, 5, 6, 7], [ 8, 9, 10, 11]])In [445]: xOut[445]: array([[ 0, 1, 2, 3, 4, 5], [ 6, 7, 8, 9, 10, 11]])y has a different shape, but shares the data buffer:
In [446]: y += 1In [447]: yOut[447]: array([[ 1, 2, 3, 4], [ 5, 6, 7, 8], [ 9, 10, 11, 12]])In [448]: xOut[448]: array([[ 1, 2, 3, 4, 5, 6], [ 7, 8, 9, 10, 11, 12]])